Copper alloy for electric and electronic instruments

ABSTRACT

A copper alloy for electric and electronic instruments, containing Ni of 1 to 3 mass %, Ti of 0.2 to 1.2 mass %, any one or both of Mg and Zr of 0.02 to 0.2 mass %, and Zn of 0.1 to 1 mass %, with the balance being Cu and unavoidable impurities, in which the copper alloy contains at least one of an intermetallic compound comprising Ni, Ti and Mg, an intermetallic compound comprising Ni, Ti and Zr, or an intermetallic compound comprising Ni, Ti, Mg and Zr, and the copper alloy has a stress relaxation rate of 20% or less after holding the alloy at 150° C. for 1,000 hours; and a method of producing the copper alloy for electric and electronic instruments.

TECHNICAL FIELD

The present invention relates to a copper alloy for electric andelectronic instruments improved in its properties.

BACKGROUND ART

Heretofore, generally, in addition to a stainless-based steel,copper-based materials such as phosphor bronze, red brass, and brass,which are excellent in electrical conductivity and thermal conductivity,have been used widely as materials for parts of electric and electronicinstruments (electrical and electronic machinery and tools).

A demand for small size and light weight of the electric and electronicinstruments, accompanied with high density mounting requirement thereof,has been increased in recent years. When the electric and electronicinstruments are made further small-sized, a contact area and thethickness of the plate used are reduced. Accordingly materials havinghigher strength are required for maintaining reliability of theinstruments equivalent to those of conventional ones. Connectors fit(contact) to one another by a given magnitude of contact pressuregenerated by deflection, (that is, deformation) of the materials toallow an electric current or information signals flow or exchangethrough the joint. Accordingly, it is a fatal defect that the fitting(joining) force is decreased as a result of decrease of the contactpressure during the use, and accordingly the connectors are unable toflow or exchange the electric current or information signals through thejoint. This decrease of fitting (joining) forces is referred to asstress relaxation characteristic (creep resistance), and copper alloysfree from deterioration of the stress relaxation characteristic, thatis, copper alloys having an excellent stress relaxation resistance, aredesired for the materials to be used for these electronic parts.

Some of the connectors may be connected to heat-generating instruments,such as CPU (Central Processing Unit) of a personal computer. Theconnector material is required to be able to promptly dissipate the heatin this case, since the fitting (joining) force is rapidly decreased byacceleration of the stress relaxation due to heating of the connectormaterial. The material is required to have a higher electricconductivity because the heat-dissipating property is ascribed to theelectric conductivity of the material. The higher electric conductivityof the material is also required from the view point of exchange ofinformation using high frequency in the future.

The material is also required to have a good bending property for makingthe electric or electronic instruments small size. Thinning theinstruments is one of the strategies for making the instruments compact,and to reduce the height of the connector (to make the connector low inthe height) is accompanied by thinning the instruments. Consequently, aconnector material having better workability is desired.

The material is desired to have high strength with good electricconductivity while it is excellent in stress relaxation resistanceproperty and bending property by the reasons as described above.Specifically, a material having a strength of 600 MPa or more, anelectric conductivity of, preferably, 50% IACS or more, a stressrelaxation rate of 20% or less after allowing to stand at 150° C. for1,000 hours, and the ratio R/t, which is an index of bending property,of 1 or less is desired. Also, a material having a strength of 650 MPaor more and an electric conductivity of 55% IACS or more is demanded.

Examples of a usual method of enhancing the strength of the metallicmaterial include a work reinforcement method, in which a working strainis introduced into the material, a solid solution reinforcement method,in which other elements are allowed to be in the solid solution, and aprecipitation reinforcement method, in which a second phase isprecipitated to harden the material.

Examples of the alloys prepared by the precipitation reinforcementmethod include a Cu—Be alloy (C17200), a Cu—Ni—Si alloy (C70250), aCu—Fe alloy (C19400) and a Cu—Cr alloy (C18040). However, while C17200alloy has a strength of 1,000 MPa or more and stress relaxation rate of20% or less with good bending property by applying a reinforcementmechanism for allowing Be to precipitate in the Cu host matrix, theelectric conductivity is as low as about 25% IACS. In addition, the useof beryllium (Be) may actually cause an environmental problem.

Although the C70250 alloy prepared by allowing an intermetallic compoundcomprising Ni—Si to precipitate in the Cu host matrix has a strength of600 MPa or more and a stress relaxation rate of 20% or less with goodbending property, it cannot give an electric conductivity of 50% IACS ormore.

Although the C19400 alloy has a strength of 600 MPa or more and anelectric conductivity of about 65% IACS by applying a reinforcementmechanism for allowing iron (Fe) to precipitate in the Cu host matrix,the desired properties for the stress relaxation rate and bendingproperty are not satisfied in the C19400 alloy.

The desired properties for the stress relaxation rate and the bendingproperty are not satisfied either in the C18040 alloy as in the C19400alloy, although the alloy has an electric conductivity of about 80% IACSand a strength of about 600 MPa.

No materials satisfying the desired properties can be obtained using anyof the precipitation reinforcement methods as described above, anddevelopments of novel materials are strongly required.

On the other hand, the strength and the electric conductivity have beenimproved in some copper alloys for the electronic instruments byallowing a Ni—Ti intermetallic compound to uniformly and finelyprecipitate in the Cu matrix.

In another example, adhesiveness between a lead frame and a resin hasbeen improved by adding aluminum (Al), silicon (Si), manganese (Mn) ormagnesium (Mg) to a Cu—Ni—Ti alloy.

However, the desired properties for the copper alloy in accordance withthe improvement of performance of recently developed electronicinstruments cannot be satisfied even by using these copper alloys, sincethe desired strength, electric conductivity and bending property as wellas stress relaxation resistance, cannot be simultaneously satisfied.

Further, in some examples, various properties of the copper alloy havebeen improved by allowing a Ni—Ti intermetallic compound to precipitatein copper.

Other and further features and advantages of the invention will appearmore fully from the following description, appropriately referring tothe accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic explanatory view for illustrating a test method ofstress relaxation property.

FIG. 2 is a schematic explanatory view for illustrating a test method ofsolder adhesiveness.

DISCLOSURE OF INVENTION

According to the present invention, there is provided the followingmeans:

(1) A copper alloy for electric and electronic instruments, comprisingNi of 1 to 3 mass %, Ti of 0.2 to 1.2 mass %, any one or both of Mg andZr of 0.02 to 0.2 mass %, and Zn of 0.1 to 1 mass %, with the balancebeing Cu and unavoidable impurities,

wherein the copper alloy contains at least one of an intermetalliccompound comprising Ni, Ti and Mg, an intermetallic compound comprisingNi, Ti and Zr, or an intermetallic compound comprising Ni, Ti, Mg andZr, and wherein the copper alloy has a stress relaxation rate of 20% orless after holding the alloy at 150° C. for 1,000 hours;

(2) The copper alloy for electric and electronic instruments accordingto the above item (1),

wherein the intermetallic compound comprising Ni, Ti and Mg, theintermetallic compound comprising Ni, Ti and Zr, or the intermetalliccompound comprising Ni, Ti, Mg and Zr has an average particle diameterin the range from 5 to 100 nm and a distribution density of from 1×10¹⁰to 1×10¹³/mm², and

wherein the crystal grain size of a host matrix of the alloy is 10 μm orless;

(3) A copper alloy for electric and electronic instruments, comprisingNi of 1 to 3 mass %, Ti of 0.2 to 1.2 mass %, any one or both of Sn andSi of 0.02 to 0.2 mass %, and Zn of 0.1 to 1 mass %, with the balancebeing Cu and unavoidable impurities,

wherein the copper alloy contains at least one of an intermetalliccompound comprising Ni, Ti and Sn, an intermetallic compound comprisingNi, Ti and Si, or an intermetallic compound comprising Ni, Ti, Sn andSi, and

wherein the copper alloy has a stress relaxation rate of 20% or lessafter holding the alloy at 150° C. for 1,000 hours;

(4) The copper alloy for electric and electronic instruments accordingto the above item (3),

wherein the intermetallic compound comprising Ni, Ti and Sn, theintermetallic compound comprising Ni, Ti and Si, or the intermetalliccompound comprising Ni, Ti, Sn and Si has an average particle diameterin the range from 5 to 100 nm and a distribution density of from 1×10¹⁰to 1×10¹³/mm², and

wherein the crystal grain size of a host matrix of the alloy is 10 μm orless;

(5) A method of producing the copper alloy for electric and electronicinstruments according to any one of the above items (1) to (4),comprising the steps of:

conducting a solution heat treatment at a temperature of 850° C. or morefor 35 seconds or less,

cooling from the solution heat treatment temperature to 300° C. at acooling rate of 50° C./sec or more,

cold-rolling at a cold rolling ratio in the range of more than 0% but50% or less, and

aging at a temperature in the range from 450 to 600° C. within 5 hours;

(6) A method of producing the copper alloy for electric and electronicinstruments according to any one of the above items (1) to (4),comprising the steps of:

conducting a solution heat treatment at a temperature of 850° C. or morefor 35 seconds or less,

cooling from the solution heat treatment temperature to 300° C. at acooling rate of 50° C./sec or more, and

aging at a temperature in the range from 450 to 600° C. within 5 hours;

(7) A copper alloy for electric and electronic instruments, comprisingNi of 1 to 3 mass % and Ti of 0.2 to 1.4 mass % with a ratio (Ni/Ti) ofthe mass percentage between Ni and Ti in the range from 2.2 to 4.7, anyone or both of Mg and Zr in a total amount of 0.02 to 0.3 mass %, and Znof 0.1 to 5 mass %, with the balance being Cu and unavoidableimpurities,

wherein the copper alloy contains at least one of an intermetalliccompound comprising Ni, Ti and Mg, an intermetallic compound comprisingNi, Ti and Zr or an intermetallic compound comprising Ni, Ti, Mg and Zr,and

wherein the copper alloy has a distribution density of the intermetalliccompound in the range from 1×10⁹ to 1×10¹³/mm², a tensile strength of650 MPa or more, an electric conductivity of 55% IACS or more, and astress relaxation rate of 20% or less after holding the alloy at 150° C.for 1,000 hours;

(8) A copper alloy for electric and electronic instruments, comprisingNi of 1 to 3 mass % and Ti of 0.2 to 1.4 mass % with a ratio (Ni/Ti) ofthe mass percentage between Ni and Ti in the range from 2.2 to 4.7, anyone or both of Mg and Zr in a total amount of 0.02 to 0.3 mass %, Zn of0.1 to 5 mass %, and Sn in the range of more than 0 mass % but 0.5 mass% or less, with the balance being Cu and unavoidable impurities,

wherein the copper alloy contains at least one of an intermetalliccompound comprising Ni, Ti and Mg, an intermetallic compound comprisingNi, Ti and Zr or an intermetallic compound comprising Ni, Ti, Mg and Zr,and

wherein the copper alloy has a distribution density of the intermetalliccompound in the range from 1×10⁹ to 1×10¹³/mm², a tensile strength of650 MPa or more, an electric conductivity of 55% IACS or more, and astress relaxation rate of 20% or less after holding the alloy at 150° C.for 1,000 hours;

(9) A copper alloy for electric and electronic instruments, comprisingNi of 1 to 3 mass % and Ti of 0.2 to 1.4 mass % with a ratio (Ni/Ti) ofthe mass percentage between Ni and Ti in the range from 2.2 to 4.7, Mgof 0.02 to 0.3 mass %, Zn of 0.1 to 5 mass %, and any one or at leasttwo of Zr, Hf, In and Ag in a total amount of more than 0 mass % but 1.0mass % or less, with the balance being Cu and unavoidable impurities,

wherein the copper alloy contains at least one of an intermetalliccompound comprising Ni, Ti and Mg, an intermetallic compound comprisingNi, Ti and Zr, or an intermetallic compound comprising Ni, Ti, Mg andZr, and

wherein the copper alloy has a distribution density of the intermetalliccompound in the range from 1×10⁹ to 1×10¹³/mm², a tensile strength of650 MPa or more, an electric conductivity of 55% IACS or more, and astress relaxation rate of 20% or less after holding the alloy at 150° C.for 1,000 hours;

(10) A copper alloy for electric and electronic instruments, comprisingNi of 1 to 3 mass % and Ti of 0.2 to 1.4 mass % with a ratio (Ni/Ti) ofthe mass percentage between Ni and Ti in the range from 2.2 to 4.7, Mgof 0.02 to 0.3 mass %, Zn of 0.1 to 5 mass %, Sn in the range of morethan 0 mass % but 0.5 mass % or less, and any one or at least two of Zr,Hf, In and Ag in a total amount of more than 0 mass % but 1.0 mass % orless, with the balance being Cu and unavoidable impurities,

wherein the copper alloy contains at least one of an intermetalliccompound comprising Ni, Ti and Mg, an intermetallic compound comprisingNi, Ti and Zr, or an intermetallic compound comprising Ni, Ti, Mg andZr, and

wherein the copper alloy has a distribution density of the intermetalliccompound in the range from 1×10⁹ to 1×10¹³/mm², a tensile strength of650 MPa or more, an electric conductivity of 55% IACS or more, and astress relaxation rate of 20% or less after holding the alloy at 150° C.for 1,000 hours; and

(11) A method of producing the copper alloy for electric and electronicinstruments according to any one of the above items (7) to (10), whichcomprises applying once or at least twice of heat treatment forprecipitation by aging at a temperature of from 450 to 650° C. within 5hours,

wherein an electric conductivity before the heat treatment forprecipitation by aging is 35% IACS or less.

Hereinafter, a first embodiment of the present invention means toinclude the copper alloys for electric and electronic instrumentsdescribed in the items (1) to (4) above and the methods of producing thecopper alloy for electric and electronic instruments described in theitems (5) to (6) above.

A second embodiment of the present invention means to include the copperalloys for electric and electronic instruments described in the items(7) to (10) above and the method of producing the copper alloy forelectric and electronic instruments described in the item (11) above.

Herein, the present invention means to include both of the above firstand second embodiments, unless otherwise specified.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is explained in detail below.

In the course of studies for strengthening the copper alloy with anintermetallic compound comprising nickel (Ni) and titanium (Ti) by aprecipitation reinforcement method in which a second phase isprecipitated, the present inventors have found that a material capableof substantially satisfying the desired properties such as the strength,electric conductivity, bending property, stress relaxation resistanceand solder adhesiveness can be produced by modifying the intermetalliccompound by adding magnesium (Mg), zirconium (Zr), tin (Sn), silicon(Si) or the like.

The electric and electronic instruments of the present invention,particularly of the first embodiment of the present invention, includeinstruments mounted for a car.

The first embodiment of the present invention will be described below.

Various properties of an alloy are remarkably improved in the presentinvention, particularly in the first embodiment of the presentinvention, by forming an intermetallic compound comprising Ni, Ti and Mg(referred to as “Ni—Ti—Mg” hereinafter), an intermetallic compoundcomprising Ni, Ti and Zr (referred to as “Ni—Ti—Zr” hereinafter), or anintermetallic compound comprising Ni, Ti, Mg and Zr (referred to as“Ni—Ti—Mg—Zr” hereinafter) precipitated in the Cu host matrix. Theseintermetallic compounds are utterly different from Ni—Ti precipitatesformed in conventional alloys, and provide quite high strength, electricconductivity and stress relaxation resistance property.

As described above, the strength is improved by precipitationstrengthening mechanism while the electric conductivity increases, whenthe Ni—Ti is finely dispersed in the Cu host matrix. However, themagnitude of reinforcement becomes quite large, as compared withprecipitation of the Ni—Ti, by allowing the Ni—Ti—Mg, the Ni—Ti—Zr orthe Ni—Ti—Mg—Zr to finely disperse individually or compositely in the Cuhost matrix. This effect permits materials having excellent strength andelectric conductivity to be obtained. This effect is exhibited even whenthe Ni—Ti is simultaneously dispersed, and the magnitude ofreinforcement is larger as the dispersion density of the Ni—Ti—Mg, theNi—Ti—Zr or the Ni—Ti—Mg—Zr is higher. In this case, the amount of thedispersion density of the Ni—Ti—Mg, the Ni—Ti—Zr or the Ni—Ti—Mg—Zr isdesirably equal to or more than that of the Ni—Ti.

The same effect as described above could be also observed when anintermetallic compound comprising Ni, Ti and Sn (referred to as“Ni—Ti—Si” hereinafter), an intermetallic compound comprising Ni, Ti andSi (referred to as “Ni—Ti—Si” hereinafter) or an intermetallic compoundcomprising Ni, Ti, Sn and Si (referred to as “Ni—Ti—Sn—Si” hereinafter)had been precipitated.

Next, the stress relaxation property will be described below. The stressrelaxation resistance property is remarkably improved when the Ni—Ti—Mg,the Ni—Ti—Zr or the Ni—Ti—Mg—Zr is finely, and individually orcompositely, dispersed in the Cu host matrix, as compared with the casewhen the Ni—Ti is finely dispersed in the host matrix. On the contrary,a stress relaxation rate of 20% or less cannot be achieved when only theNi—Ti is precipitated.

This may be interpreted that, since the Ni—Ti—Mg, the Ni—Ti—Zr or theNi—Ti—Mg—Zr has a different crystal structure from that of the Ni—Ticompound, the stress relaxation resistance property is remarkablyimproved by finely dispersing such intermetallic compound having thedifferent crystal structure in the Cu host matrix.

Stress relaxation is a phenomenon by which the strain is released byallowing dislocations in the metal to move. Since the Ni—Ti—Mg, theNi—Ti—Zr or the Ni—Ti—Mg—Zr has a larger force for fixing thedislocations than the Ni—Ti compound, the stress is hardly relaxed inthe alloy containing the former intermetallic compound.

The same phenomenon is confirmed in the alloy containing the Ni—Ti—Sn,the Ni—Ti—Si or the Ni—Ti—Sn—Si. A material being excellent in thestress relaxation resistance property and having the desired propertiescan be produced by forming these precipitates in the alloy.

The desired properties can be obtained by prescribing the amount ofcomponents as described below.

The content of Ni is limited in the range from 1 to 3 mass %, because asufficient strength cannot be obtained due to a small amount ofreinforcement by precipitation when the content of Ni is too small, andthe stress relaxation resistance property cannot be improved. On theother hand, a too large amount of Ni causes a decrease of the electricconductivity even after the aging treatment because an excess amount ofNi is solute in the host matrix. In addition, the alloy cannot beproduced by an industrially stable process since the temperature for thesolution heat treatment (solid solution treatment) comes to near themelting temperature. Further, it is another problem that the bendingproperty becomes poor due to coarsening of crystal grains since a longtime of the solution heat treatment at a higher temperature isnecessary. The content of Ni is preferably in the range from 1.4 to 2.6mass %, and more preferably in the range from 1.8 to 2.3 mass %.

The content of Ti is limited in the range from 0.2 to 1.2 mass %because, when the content of Ti is too small, a sufficient strengthcannot be obtained due to a small amount of reinforcement byprecipitation, and the stress relaxation resistance property cannot beimproved. On the other hand, a too large amount of Ti causes a decreaseof the electric conductivity even after the aging treatment because anexcess amount of Ti is solute in the host matrix. In addition, it isanother problem that the bending property becomes poor due to coarseningof crystal grains since a long time of the solution heat treatment at ahigher temperature is necessary. The content of Ti is preferably in therange from 0.5 to 1.1 mass %, more preferably in the range from 0.7 to1.0 mass %.

Mg forms an intermetallic compound (also referred to as a “precipitate”hereinafter) together with Ni, Ti, Zr and the like, and improves thestrength, electric conductivity, bending property, stress relaxationresistance property, and the like. The content of Mg is limited in therange from 0.02 to 0.2 mass % because, when the content of Mg is toosmall, the stress relaxation rate becomes poor due to a small amount ofthe precipitate comprising Ni, Ti and Mg or the like. On the other hand,the bending property becomes poor due to coarsening of crystal grainswhen the amount of Mg is too large, since a high temperature and longtime of the solution heat treatment is required. In addition, theelectric conductivity is poor even by applying an aging treatment sinceexcess Mg remains in the solid solution. The stress relaxation rate alsobecomes poor probably due to a different proportion of constitutionelements in the precipitate. The content of Mg is preferable in therange from 0.05 to 0.15 mass %, and more preferable in the range from0.08 to 0.12 mass %.

The content of Zr is limited in the range from 0.02 to 0.2 mass % by thesame reason as limiting the content of Mg. The content of Zr ispreferably in the range from 0.05 to 0.15 mass %, and more preferably inthe range from 0.08 to 0.12 mass %.

Sn forms a precipitate together with Ni, Ti and Si, and improves thestrength, electric conductivity, bending property, stress relaxationresistance property, and the like. The content of Sn is limited in therange from 0.02 to 0.2 mass % because, when the amount of Sn is toosmall, the stress relaxation rate becomes poor due to a too small amountof the precipitate comprising Ni, Ti and Sn or the like. The electricconductivity and bending property become poor when the amount of Sn istoo large since excess Sn remains in the solid solution. The stressrelaxation rate is also poor probably due to the effect of a differentproportion of constitution elements in the precipitate. The content ofSn is preferably in the range from 0.05 to 0.15 mass %, and morepreferably in the range from 0.08 to 0.12 mass %.

The content of Si is limited in the range from 0.02 to 0.2 mass %because, when the content of Si is too small, the strength and stressrelaxation resistance property become poor due to a small amount of theprecipitate comprising Ni, Ti and Si or the like, and the electricconductivity becomes poor since excess Ni remains in the solid solution.The electric conductivity decreases when the content of Si is too large,since excess Si is solute in the copper host matrix when a desiredprecipitate is formed. The content of Si is preferably in the range from0.05 to 0.15 mass %, and more preferably in the range from 0.08 to 0.12mass %.

The average particle diameter of the intermetallic compound is usuallyin the range from 1 to 100 nm, preferably in the range from 5 to 100 nm,as a diameter of corresponding spheres having an equal volume to thevolume of the intermetallic compound. A distribution density in therange from 1×10¹⁰ to 1×10¹³/mm² is preferable since the alloy becomesexcellent in the strength and bending property.

The effect for improving the strength is insufficient when the averageparticle diameter of the intermetallic compound is too small, while theintermetallic compound does not contribute for improving the strength byprecipitation when the average particle diameter is too large. Theaverage particle diameter is further preferably in the range from 10 to60 nm, and more preferably in the range from 20 to 50 nm. The averageparticle diameter of the intermetallic compound is controlled by theheating temperature and heating time in the aging step. A highertemperature or longer time gives a larger average particle diameter. Onthe contrary, a lower temperature or shorter time gives a smalleraverage particle diameter.

When the distribution density of the intermetallic compound is toosmall, the effect for improving the strength by precipitation becomesinsufficient, while coarse precipitates tend to be formed at grainboundaries to deteriorate the bending property when the distributiondensity is too large. The distribution density is further preferably inthe range from 3×10¹⁰ to 5×10¹²/mm², more preferably in the range from1×10¹¹ to 3×10¹²/mm². The distribution density of the intermetalliccompound is controlled by appropriately combining the conditions for theheat treatment for precipitation by aging, cold working that is appliedprior to the heat treatment for precipitation by aging, solution heattreatment and hot rolling. The distribution density of the precipitatesis calculated as the number of the precipitates per unit area(number/mm²) by measuring the number of the precipitates with atransmission electron microscope observation.

The crystal grain size of the host matrix is preferably 10 μm or less.The bending property is deteriorated when the crystal grain size of thehost matrix is too large. The preferable diameter is 5 μm or less. Whilethe lower limit of the crystal grain size of the host matrix is notparticularly restricted, it is usually 3 μm. The crystal grain size asused herein refers to the longer diameter of the grains. The crystalgrain size of the host matrix is controlled by the heating temperatureand heating time in the solution heat treatment step. The highertemperature or longer time gives a larger crystal grain size, while thelower temperature or shorter time gives a smaller crystal grain size.

Zn improves adhesiveness of a solder and prevents plating from beingpeeled. A preferable use of the present invention is electronicinstruments, and most of parts thereof are joined with a solder.Accordingly, improved adhesiveness of the solder causes an improvementof reliability of the parts, which is an essential property for applyingto the electronic instruments. The effect of Zn has been discussed inrecent years (for example, see Sindo Gijutu Kennkyuukai Shi (Journal ofJapan Copper and Brass Association), Vol. 026 (1987), pp. 51-56). Thisreport describes that adding Zn improves heat-peeling resistance. Theheat-peeling resistance is considered to be improved by adding Zn,because voids are suppressed from being generated, and they aresuppressed from being concentrated at the interface between the hostmaterial comprising Ni and Si and diffusion layers. While the exampleabove is for alloys of precipitation type such as Cu—Ni—Si alloys, thesame effect has been confirmed in the first embodiment of the presentinvention.

The content of Zn is limited in the range form 0.1 to 1 mass % because,when the content of Zn is too small, the heat-peeling resistanceproperty is not exhibited, while the electric conductivity is reducedwhen the content of Zn is too large. The content of Zn is preferably inthe range from 0.2 to 0.8 mass %, more preferably in the range from 0.35to 0.65 mass %.

The stress relaxation rate of the copper alloy for electric andelectronic instruments according to the present invention, particularlyaccording to the first embodiment of the present invention, is 20% orless when the alloy is held at 150° C. for 1,000 hours. The rate ispreferably 18% or less, and more preferably 16% or less; and althoughthe lower limit is not particularly restricted, it is 10%.

The copper alloy according to the present invention, particularlyaccording to the first embodiment of the present invention, is producedthrough the steps comprising, for example, hot rolling, cold rolling,solution heat treatment and aging treatment, and if necessary finishcold rolling and stress-relief annealing. The intermetallic compound maybe adjusted within the range of the present invention by controlling theconditions, such as the solution heat treatment (temperature) andcooling rate in the subsequent cooling step, in the production process.The hot rolling temperature may be, for example, in the range from 850to 1,000° C., and the subsequent cold rolling may be conducted at theprocessing ratio of, for example, 90% or more.

An embodiment of the production method according to the presentinvention, particularly according to the first embodiment of the presentinvention, comprises the steps of: conducting a solution heat treatmentat 850° C. or more within 35 seconds, cooling from the solution heattreatment temperature to 300° C. at a cooling rate of 50° C./sec ormore, cold-rolling at a rolling ratio in the range of more than 0% but50% or less, and aging at a temperature in the range from 450 to 600° C.within 5 hours. Another embodiment of the production method according tothe present invention, particularly according to the first embodiment ofthe present invention, comprises the steps of: conducting a solutionheat treatment at 850° C. or more within 35 seconds, cooling from thesolution heat treatment temperature to 300° C. at a cooling rate of 50°C./sec or more, and aging at a temperature from 450 to 600° C. within 5hours. The finish cold rolling ratio thereafter is preferably 30% orless.

The solution heat treatment is preferably conducted at 850° C. or morewithin 35 seconds in the present invention, particularly in the firstembodiment of the present invention. Recrystallization does not occurwhen the solution heat treatment temperature is too low, resulting inremarkably deterioration in bending property. Further, solid solutionsare not formed even by recrystallization to make it impossible to attainthe highest precipitation reinforcement in the subsequent aging step dueto the presence of crystallized grains, coarse precipitates or the like.Furthermore, deterioration of the bending property is also apprehendeddue to the presence of residual crystals, precipitates or the like. Thealloy is preferably cooled to 300° C. at a cooling rate of 50° C./sec ormore after the solution heat treatment, because when the cooling rate istoo small, the elements once incorporated into the solid solution areprecipitated. Such precipitates do not contribute to strengthening dueto their coarsening.

The upper limit of the solution heat treatment temperature is preferably1,000° C. or less from the view point of fuel cost. Too long solutionheat treatment time causes deterioration of the bending property due tocoarsening of crystal grains. The solution heat treatment time ispreferably within 25 seconds.

It is preferably that the cold rolling after the solution heat treatmentis not conducted, or is conducted at a cold rolling ratio of 50% orless. The higher cold rolling ratio causes deterioration of the bendingproperty. The ratio is more preferably 30% or less.

The aging treatment is preferably conducted at a temperature from 450 to600° C. within 5 hours. Too low aging treatment temperature results ininsufficient strength due to an insufficient amount of precipitates,while too high aging treatment temperature does not contribute to thestrength since the precipitates get coarse. The aging treatmenttemperature is preferably in the range from 480 to 560° C.

The direction of final plastic working as used in the present invention,in particular in the first embodiment of the present invention, refersto the direction of rolling when the rolling is the finally carried outplastic working, or to the direction of drawing when the drawing (lineardrawing) is the plastic working finally carried out. The plastic workingrefers to workings such as rolling and drawing, but working for thepurpose of leveling (vertical leveling) using, for example, a tensionleveler, is not included in this plastic working.

Next, the second embodiment of the present invention will be describedbelow.

Various properties of the alloy are remarkably improved in the presentinvention, particularly in the second embodiment of the presentinvention, by forming an intermetallic compound comprising Ni, Ti and Mg(referred to as “Ni—Ti—Mg” hereinafter), an intermetallic compoundcomprising Ni, Ti and Zr (referred to as “Ni—Ti—Zr” hereinafter), or anintermetallic compound comprising Ni, Ti, Mg and Zr (referred to as“Ni—Ti—Mg—Zr” hereinafter) precipitated in the Cu host matrix. Theseintermetallic compounds are utterly different from Ni—Ti precipitatesformed in conventional alloys, and provide quite high strength, electricconductivity and stress relaxation resistance property.

As described above, the strength is improved by precipitationstrengthening mechanism while the electric conductivity increases, whenthe Ni—Ti is finely dispersed in the Cu host matrix. However, themagnitude of reinforcement becomes quite large, as compared withprecipitation of the Ni—Ti, by allowing the Ni—Ti—Mg, the Ni—Ti—Zr orthe Ni—Ti—Mg—Zr to finely disperse individually or compositely in the Cuhost matrix. This effect permits materials having excellent strength andelectric conductivity to be obtained. This effect is exhibited even whenthe Ni—Ti is simultaneously dispersed, and the magnitude ofreinforcement is larger as the dispersion density of the Ni—Ti—Mg, theNi—Ti—Zr or the Ni—Ti—Mg—Zr is higher. In this case, the amount of thedispersion density of the Ni—Ti—Mg, the Ni—Ti—Zr or the Ni—Ti—Mg—Zr isdesirably equal to or more than that of the Ni—Ti. These Ni—Ti baseternary or multi-component compounds can contribute to the improvementof the stress relaxation resistance property.

Both the strength and stress relaxation resistance property may beimproved, without reducing the electric conductivity, by allowingappropriate amounts of Mg or Sn to be in the solid solution.

The desired properties may be obtained by prescribing the amount ofcomponents as described below.

The content of Ni is limited in the range from 1 to 3 mass %, because asufficient strength cannot be obtained due to a small amount ofreinforcement by precipitation when the content of Ni is too small, andthe stress relaxation resistance property cannot be improved. On theother hand, a too large amount of Ni causes a decrease of the electricconductivity even after the aging treatment because an excess amount ofNi is solute in the host matrix. In addition, the alloy cannot beproduced by an industrially stable process since the temperature for thesolution heat treatment comes to near the melting temperature. Further,it is another problem that the bending property becomes poor due tocoarsening of crystal grains since a long time of the solution heattreatment at a higher temperature is necessary. The content of Ni ispreferably in the range from 1.2 to 2.4 mass %, and more preferably inthe range from 1.4 to 2.2 mass %.

The content of Ti is limited in the range from 0.2 to 1.4 mass %because, when the content of Ti is too small, a sufficient strengthcannot be obtained due to a small amount of reinforcement byprecipitation, and the stress relaxation resistance property cannot beimproved. On the other hand, a too large amount of Ti causes a decreaseof the electric conductivity even after the aging treatment because anexcess amount of Ti is solute in the host matrix. In addition, it isanother problem that the bending property becomes poor due to coarseningof crystal grains since a long time of the solution heat treatment at ahigher temperature is necessary. The content of Ti is preferably in therange from 0.3 to 1.0 mass %, more preferably in the range from 0.35 to0.9 mass %.

The ratio (Ni/Ti) in the mass percentage between Ni and Ti is limited inthe range form 2.2 to 4.7 because both elements should be blended in anappropriate ratio in order to allow the multi-component compounds, suchas Ni—Ti base or Ni—Ti—Mg base compounds, to be precipitated as acompound having a stoichiometric composition in Cu. The ratio out ofthis range is not preferable since the solute elements do not contributeto the formation of the compound and they reduce the electricconductivity by being in the solid solution. The ratio (Ni/Ti) ispreferable in the range from 2.6 to 3.8, more preferably in the rangeform 2.8 to 3.6.

Mg forms an intermetallic compound (also referred to as a “precipitate”hereinafter) together with Ni, Ti and Zr, and improves the strength,electric conductivity, bending property, stress relaxation resistanceproperty, and the like. The content of either or both of Mg and Zr intotal is limited in the range from 0.02 to 0.3 mass % because, when thecontent is too small, the strength becomes poor since the amount of theprecipitate comprising Ni, Ti and Mg, the precipitate comprising Ni, Tiand Zr and/or the precipitate comprising Ni, Ti, Mg and Zr is small.When the content is too large, on the other hand, a high temperature anda long time is necessary for the solution heat treatment, and crystalgrains get coarse to deteriorate the bending property. In addition,excess Mg and/or Zr remains in the solid solution even by conducting anaging treatment, and the electric conductivity is poor. The content ofeither or both of Mg and Zr in total is preferably in the range from0.05 to 0.18 mass %, and more preferably in the range from 0.08 to 0.15mass %.

The distribution density of the intermetallic compound in the range from1×10⁹ to 1×10¹³/mm² is preferable because the ratio gives excellentstrength and bending property.

When the distribution density of the intermetallic compound is toosmall, the effect for improving the strength by precipitation becomesinsufficient, while coarse precipitates tend to be formed at grainboundaries to deteriorate the bending property when the distributiondensity is too large. The distribution density is further preferably inthe range from 3×10¹⁰ to 5×10¹²/mm², more preferably in the range from1×10¹¹ to 3×10¹²/mm². The distribution density of the intermetalliccompound is controlled by appropriately combining the conditions for theheat treatment for precipitation by aging, cold working that is appliedprior to the heat treatment for precipitation by aging, solution heattreatment and hot rolling.

The distribution density of the precipitates is calculated as the numberof the precipitates per unit area (number/mm²) by measuring the numberof the precipitates with a transmission electron microscope observation.

Zn improves adhesiveness of a solder and prevents plating from beingpeeled. A preferable use of the present invention is electronicinstruments, and most of parts thereof are joined with a solder.Accordingly, improved adhesiveness of the solder causes an improvementof reliability of the parts, which is an essential property for applyingto the electronic instruments. The effect of Zn has been discussed inrecent years (for example, see Sindo Gijutu Kennkyuukai Shi (Journal ofJapan Copper and Brass Association), Vol. 026 (1987), pp. 51-56). Thisreport describes that adding Zn improves heat-peeling resistance. Theheat-peeling resistance is considered to be improved by adding Zn,because voids are suppressed from being generated, and they aresuppressed from being concentrated at the interface between the hostmaterial comprising Ni and Si and diffusion layers. While the exampleabove is for alloys of precipitation type such as Cu—Ni—Si alloys, thesame effect has been confirmed in the second embodiment of the presentinvention.

The content of Zn is limited in the range form 0.1 to 5 mass % because,when the content of Zn is too small, the heat-peeling resistanceproperty is not exhibited, while the electric conductivity is reducedwhen the content of Zn is too large. The content of Zn is preferably inthe range from 0.2 to 3.0 mass %, more preferably in the range from 0.3to 1 mass %.

Sn is solute in the solid solution with Mg and serves for improving thestress relaxation resistance property. The element is effective forsuppressing coarse Ni—Ti from precipitating in the cooling step of thesolution heat treatment and the hot rolling conducted at a temperatureof 900° C. or more, and resulting in improving the strength by enhancingthe magnitude of precipitation hardening. Since the alloy system of thepresent invention permits an ideal solid solution state, in which almostall atoms are in the solid solution, to be formed at a temperature ashigh as 900° C. or more, it is important for attaining goodprecipitation reinforcement to prevent coarse compounds fromprecipitating at a high temperature where atomic diffusion is rapid.This state is favorably realized by adding Sn, and the strength andstress relaxation resistance property are improved by agingprecipitation. Further, Sn can prevent coarse compounds fromprecipitating at grain boundaries, to improve the bending property.While the effect is enhanced as the content of Sn is larger, theelectric conductivity becomes poor when the content of Sn is too largesince excess Sn remains in the solid solution. The content of Sn isgenerally in the range of more than 0 mass % but 0.5 mass % or less,preferably in the range from 0.05 to 0.25 mass %.

Zr, Hf, In and Ag improve the strength, electric conductivity, stressrelaxation resistance property, and the like by forming precipitatestogether with Ni and Ti. While the effect is enhanced as the contents ofthese elements are higher, the bending property is deteriorated due tocoarsening of crystal grains when the contents exceed 1.0 mass % sincethe solution heat treatment at a high temperature for a long time isnecessary. In addition, the electric conductivity is also deterioratedsince excess atoms remain in the solid solution even by conducting anaging treatment. The total content of Zr, Hf, In and Ag is in the rangeof more than 0 mass % but 1.0 mass % or less, preferably in the rangefrom 0.05 to 0.5 mass %, and more preferably in the range from 0.07 to0.3 mass %.

The tensile strength of the copper alloy for the electric and electronicinstruments of the present invention, particularly of the secondembodiment of the present invention, is 650 MPa or more. The tensilestrength is preferably 750 MPa or more. Although the upper limit is notparticularly restricted, it is generally 850 MPa.

The electric conductivity of the copper alloy for the electric andelectronic instruments of the present invention, particularly of thesecond embodiment of the present invention, is 55% IACS or more. Theelectric conductivity is preferably 60% IACS or more. Although the upperlimit is not particularly restricted, it is generally 70% IACS.

The stress relaxation rate of the copper alloy for electric andelectronic instruments according to the present invention, particularlyaccording to the second embodiment of the present invention, is 20% orless when the alloy is held at 150° C. for 1,000 hours. The rate ispreferably 18% or less, and more preferably 16% or less; and althoughthe lower limit is not particularly restricted, it is 10%.

The copper alloy according to the present invention, particularlyaccording to the second embodiment of the present invention, is producedby the steps of: for example, casting, homogenization treatment, hotrolling, cold rolling, solution heat treatment and aging treatment, and,if necessary, finish cold rolling and stress-relief annealing.

While the cooling rate is preferably increased for preventing soluteelements from segregating at finally solidified portions at the time ofcasting, a too rapid cooling rate may form cavities in a resulting ingotto deteriorate the quality or to generate internal defects by enhancingthe internal stress of a resulting ingot. Accordingly, the cooling rateis preferably in the range of 1 to 100° C./sec, more preferably in therange from 10 to 80° C./sec.

The alloy is preferably homogenized by annealing at a temperature abovethe solution heat temperature in accordance with the atomic weight ofthe solute in the alloy in order to form a solid solution while coarseNi—Ti base compounds are prevented from precipitating. Homogenizingannealing at a higher temperature than necessary is not preferable sinceoxidation of elements such as Ti, Mg, Zr and Hf is facilitated todeteriorate such quality as adhesiveness of plating. Accordingly, thetemperature for holding an ingot before hot rolling is usually in therange from 800 to 1,050° C., preferably from 900 to 1,000° C., and morepreferably from 960 to 1,000° C. The holding time is preferably in therange from 1 hour or more to 10 hours or less in order to make theelements to be solute sufficiently in the solid solution and preventoxidization. The heating rate is preferably 3° C./min or more, sincecoarse precipitates are formed when the heating rate to the holdingtemperature is slow.

The cooling rate is usually increased by showering cold water at atemperature of 20° C. or lower or other methods in order to suppresssolute atoms from precipitating in the cooling step during the time fromthe start to the end of the hot rolling. The cooling rate is preferablyin the range from 5 to 300° C./sec, more preferably 50 to 300° C./sec.

Excellent strength, electric conductivity, stress relaxation resistanceproperty and bending property may be obtained by conducting a heattreatment(s) for precipitation by aging once or twice at a temperaturein the range from 450 to 650° C. for within 5 hours during the step forreducing the thickness of the alloy by cold rolling.

The strength and electric conductivity become insufficient due to toolow heat treatment temperature for precipitation by aging, while theprecipitates do not contribute to the strength when the temperature istoo high since the precipitates get coarse. The temperature ispreferably in the range from 480 to 620° C.

The heat treatment time for precipitation by aging is preferably within4 hours, and the lower limit thereof is 0.1 hour.

The strength and electric conductivity are further improved byconducting the heat treatment steps for precipitation by aging two ormore times with a cold rolling step between the heat treatment steps.The density of dislocations to be introduced in the next cold rollingstep may be increased by the fine compounds precipitated in the firstaging step, and the dislocations serve as sites for forming a nucleusfor precipitation in the second heat treatment step and thereafter forprecipitation by aging. Consequently, the strength is further enhancedby increasing the density of the precipitates. Accordingly, thecondition for the first aging step is preferably employed so that thehighest density of the precipitates is obtained.

The effect of the heat treatment for precipitation by aging isremarkably emphasized by increasing the amount of the solute atoms inthe solid solution as large as possible before precipitation of theatoms. In other words, properties such as high strength, high electricconductivity and high stress relaxation resistance may be manifested byforming a good solid solution state before the heat treatment forprecipitation by aging in order to permit highly dense and fineprecipitation state to be realized by the heat treatment forprecipitation by aging. The electric conductivity is usually used as anindex of the degree of the solid solution, and the strength and stressrelaxation resistance property are improved when the electricconductivity before the heat treatment for precipitation by aging is 35%IACS or less. The strength and stress relaxation resistance become poorwhen the electric conductivity is more than 35% IACS, since the amountof the solute atoms that are finely precipitated in a high density issmall after the heat treatment for precipitation by aging. It is morepreferably 30% IACS or less.

The direction of final plastic working as used in the present invention,in particular in the second embodiment of the present invention, refersto the direction of rolling when the rolling is the finally carried outplastic working, or to the direction of drawing when the drawing (lineardrawing) is the plastic working finally carried out. The plastic workingrefers to workings such as rolling and drawing, but working for thepurpose of leveling (vertical leveling) using, for example, a tensionleveler, is not included in this plastic working.

The copper alloy for the electric and electronic instruments of thepresent invention may be favorably used, for example, for connectors,terminals, relays and switches, and lead frames, although itsapplication is not restricted thereto.

According to the present invention, it is possible to provide a novelcopper alloy for the electric and electronic instruments excellent inthe strength, electric conductivity, bending property and stressrelaxation resistance property as well as adhesiveness of solder.

The copper alloy of the present invention, in particular of the firstembodiment of the present invention, has performance of 600 MPa or morein the strength, 20% or less in the stress relaxation rate after holdingat 150° C. for 1,000 hours, 50% IACS or more of the electricconductivity, and 1 or less of the (R/t) ratio, which is an index of thebending property. The metallic material is suitable for terminals,connectors, and relays and switches for the electric and electronicinstruments and car-mounting parts.

The copper alloy of the present invention, in particular of the secondembodiment of the present invention, has performance of 650 MPa or morein the strength, 20% or less in the stress relaxation rate after holdingat 150° C. for 1,000 hours and 55% IACS or more of the electricconductivity. The metallic material is suitable for the terminals,connectors, and relays and switches for the electric and electronicinstruments.

The present invention will be described in more detail based on examplesgiven below, but the invention is not meant to be limited by these.

EXAMPLES Example 1

Alloys comprising Ni, Ti, Mg, Zr, Zn, Sn and Si in the amounts as shownin Tables 1 to 4 with the balance of Cu were melted in a high frequencymelting furnace, and each molten alloy was cast with a cooling rate inthe range from 10 to 30° C./sec to give an ingot with a thickness of 30mm, a width of 100 mm and a length of 150 mm. After holding the ingot at1,000° C. for 1 hour, it was finished to a hot roll plate with athickness of about 10 mm using a hot rolling machine. Oxide films wereremoved by shaving both surfaces of the hot roll plate to a depth ofabout 1.0 mm. The plate was then cold-rolled to a thickness of 0.29 mmfollowed by subjecting to a solution heat treatment at 950° C. for 15second in an inert gas, and was cooled to 300° C. over about 3 seconds(a cooling rate of about 300° C./sec) after the solution heat treatment.The plate was further cold-rolled to a thickness of 0.23 mm followed byan aging treatment at 550° C. for 2 hours. The plate was rolled to athickness of 0.2 mm followed by low temperature annealing at 350° C. for2 hours to provide plate materials of Examples 1 to 18 and 40 to 57 ofthe present invention, and Comparative Examples 21 to 34, 60 to 67 and70 to 73, as test pieces.

Each plate material thus obtained was investigated with respect to [1]tensile strength, [2] electric conductivity, [3] stress relaxationproperty (SR), [4] bending property (R/t), [5] crystal grain size (GS),[6] size and density of precipitates (PPT) and [7] adhesiveness ofsolder, by the methods described below. The measuring methods forrespective evaluation items are as follows.

[1] Tensile Strength (TS)

Three JIS-13B test pieces cut in the direction parallel to the rolldirection were measured according to JIS-Z2241, and an average value(MPa) was obtained.

[2] Electric Conductivity (EC)

Test pieces with a dimension of 10×150 mm was prepared by cutting theplate in the direction parallel to the roll direction, and the electricconductivity of two of the test pieces was measured by the four-probemethod in a constant-temperature chamber controlled at 20° C. (±1° C.)to obtain an average value (% IACS). The distance between the probes was100 mm.

[3] Stress Relaxation Property (SR)

According to the Electronic Materials Manufacturers Association of JapanStandard EMAS-3003, the stress relaxation property was measured at 150°C. for 1,000 hours. FIG. 1 is an explanatory view for illustrating thetest method of stress relaxation property. FIG. 1(a) is an explanatoryview for illustrating the measuring method of the initial deflectionamount δ₀. In FIG. 1(a), the reference numeral 1 denotes a test piece,and the reference numeral 4 denotes a sample table. A load of 80% of0.2% yield strength (proof stress) was applied as an initial stressusing a cantilever method. And then, after the test piece was kept at150° C. for 1,000 hours, it changed its shape so as to return to theposition represented by reference numeral 2 in FIG. 1(b). The referencenumeral 3 in FIG. 1(b) denotes the position of the test piece withoutdeflection. The permanent deflection δ_(t) is represented by H_(t)−H₁.

The stress relaxation rate (%) is represented by δ_(t)/δ₀×100. This testis used for assessing the stress change under a constant strain for along time when it is used for a terminal material or the like, and thealloy is considered to be excellent as the stress relaxation rate issmaller.

[4] Bending Property (R/t)

The plate material was cut in a dimension of 10 mm in the width and 25mm in the length (the direction of the length parallel to the rolldirection is defined as GW and the direction of the length perpendicularto the roll direction is defined as BW), the plate was bent with abending radius R=0 at an angle of W (90°), and the presence of cracks atthe bent portion was observed using an optical microscope with 50 timesmagnification. As an evaluation criterion, a critical bending radiusgiving no cracks was measured and was expressed by R/t (R: bendingradius, t: thickness of the plate).

[5] Crystal Grain Size (GS)

The crystal texture before the final processing step was observed usinga scanning electron microscope (magnification of 200 to 1,000 times),and the crystal grain size was measured by the cut method according toJIS-H0501.

[6] Precipitate (PPT)

The test material was punched to give a material with a diameter of 3mm, and the punched material was polished by a twin-jet polishingmethod. A photograph of the polished sample was taken using atransmission electron microscope with an acceleration voltage of 300 kVand a magnification of 5,000 to 500,000 times, and the grain size anddensity of the precipitates were measured based on the photograph. Localdeviation of the number of the grains was eliminated by counting thenumber with n=10 (n denotes the number of observation spots), when thegrain size and density were measured. The number obtained was convertedinto the number per unit area (number/mm²).

[7] Adhesiveness of Solder

Adhesiveness of solder was tested according to the explanatory view asschematically illustrated in FIG. 2. The test piece was cut into a sizeof 20 mm×20 mm, and the surface of the material was subjected to anelectrolytic degreasing, as a pre-treatment, to obtain a material 13with a thickness of 6 mm. A eutectic solder of Sn—Pb was piled on thesurface of the material 13 to provide a solder portion 12. An iron wire11 with a diameter φ of 2 mm (a length of about 100 mm) prepared bycoating a Fe wire with Cu was fixed to the solder portion so that thematerial 13 was perpendicular to the wire 11 (FIG. 2(a)).

The test piece to which the wire 11 was joined was heated in air, andsolder joining strength between the iron wire 11 and the material 13 wasmeasured before and after the heating. The heating condition was at 150°C. for 500 hours in the constant temperature chamber. After taking outof the chamber, the test piece was sufficiently and gradually cooled(annealed) with air, and the tensile strength was tested in thedirections of the arrow as shown in FIG. 2(b) to measure the load. Thetensile strength was measured at room temperature with a load cell speedof 10 mm/min. The tensile strength was determined when the test material13 was peeled from the interface of the solder portion 12 and the testmaterial wire 11. The sample in which the test material was not peeledfrom the interface but the iron wire 11 was pulled from the solderportion 12 was not considered to be the object of evaluation, sinceadhesiveness between the iron wire 11 and the solder was judged to bepoor.

The tensile strength before the heat treatment was also measured asdescribed above, to determine each strength of the test material 13before and after the heat treatment. The strength was evaluated as “◯”when the proportion of decrease of the strength was 50% or less, and thestrength was evaluated as “x” when the proportion of decrease of thestrength was 50% or more. Solderability was considered to be excellentwith high reliability when the joining strength did not decrease withtime (or the material had a high residual strength).

The precipitate was identified by an observation using a transmissionelectron microscope. Five to ten precipitates were analyzed with an EDXanalyzer (energy dispersive apparatus) attached to the transmissionelectron microscope to confirm the analysis peaks of Ni, Ti, Mg, Zr, Snand Si. Diffraction patterns were photographed with the transmissionelectron microscope, and it was confirmed that the precipitates gave adifferent diffraction pattern from that in which the Ni—Ti precipitatewas formed. That is, the different diffraction pattern shows that aprecipitate other than Ni—Ti was formed. The diffraction pattern wasidentified and evaluated by selecting crystal grains containing 10 to100 precipitates.

The results of evaluations [1] to [7] are also summarized in Tables 1 to4. TABLE 1 Ti PPT Adhesiveness This Ni (mass Mg Zr Zn TS EC SR R/t R/tGS PPT (×10¹⁰/ of invention (mass %) %) (mass %) (mass %) (mass %) (MPa)(% IACS) (%) (GW) (BW) (μm) (nm) mm²) solder 1 1.55 0.57 0.08 — 0.51 60155.3 19 0.5 0.5 4.4 20 21 ◯ 2 2.11 0.78 0.12 — 0.55 685 52.7 18 0.5 0.54.8 22 15 ◯ 3 2.54 0.94 0.14 — 0.42 702 50.8 16 0.5 0.5 4.7 20 6 ◯ 42.90 1.07 0.18 — 0.44 732 48.2 14 1.0 1.0 4.9 21 16 ◯ 5 1.56 0.58 — 0.070.51 605 55.7 17 0.5 0.5 4.8 20 163 ◯ 6 2.08 0.77 — 0.11 0.25 675 52.015 0.5 0.5 4.8 23 65 ◯ 7 2.51 0.93 — 0.13 0.55 694 50.2 14 0.5 0.5 4.941 156 ◯ 8 2.95 1.09 — 0.19 0.60 745 49.0 12 1.0 1.0 4.1 20 5 ◯ 9 2.010.74 0.05 — 0.44 681 53.8 19 0.5 0.5 4.2 23 5 ◯ 10 2.10 0.78 0.11 — 0.50710 51.7 16 0.5 0.5 4.3 33 15 ◯ 11 2.14 0.79 — 0.05 0.52 723 50.8 18 0.50.5 4.3 22 54 ◯ 12 2.15 0.80 — 0.05 0.46 727 50.6 15 0.5 0.5 4.4 21 62 ◯13 2.02 0.75 0.07 0.08 0.52 684 53.5 18 0.5 0.5 4.4 23 46 ◯ 14 2.05 0.760.10 0.10 0.51 694 52.9 14 0.5 0.5 4.8 12 5 ◯ 15 2.01 0.74 0.06 0.080.50 681 53.8 19 0.5 0.5 4 13 165 ◯ 16 2.17 0.80 0.09 0.06 0.70 733 50.115 0.5 0.5 4.2 33 6 ◯ 17 2.10 0.58 0.10 — 0.23 710 51.7 17 0.5 0.5 4.9 812 ◯ 18 2.11 0.55 — 0.11 0.66 714 51.5 16 0.5 0.5 4.3 32 165 ◯

TABLE 2 Ni Ti Mg Adhesiveness Comparative (mass (mass (mass Zr Zn TS ECSR R/t R/t GS PPT PPT of example %) %) %) (mass %) (mass %) (MPa) (%IACS) (%) (GW) (BW) (μm) (nm) (×10¹⁰/mm²) solder 21 0.88 0.33 — — 0.45506 59.3 41 0.5 0.5 4.2 23 123 ◯ 22 3.30 1.22 — — 0.34 701 38.2 33 2.02.0 12.4 24 15 ◯ 23 3.51 0.38 — — 0.44 488 32 48 1.5 1.5 13.3 22 53 ◯ 242.91 2.50 — — 0.54 685 32.7 33 2.0 2.0 13.2 12 6 ◯ 25 2.20 0.81 0.01 —0.55 702 50.8 35 0.5 0.5 4.8 43 53 ◯ 26 2.10 0.78 0.55 — 0.55 732 42.325 2.0 2.0 4.5 34 125 ◯ 27 2.08 0.77 — 0.01 0.34 622 56.0 40 1.0 1.012.5 23 265 ◯ 28 2.12 0.79 — 0.60 0.55 633 43.6 22 2.0 2.0 10.9 44 46 ◯29 2.11 0.78  0.005  0.007 0.23 612 55.4 44 1.0 1.0 11.5 45 15 ◯ 30 2.080.77 0.56 0.66 0.30 622 41.6 28 2.0 2.0 12.2 23 156 ◯ 31 2.53 0.94 0.20— — 721 38.1 18 1.0 1.0 4.4 32 22 X 32 2.10 0.78 — 0.13 — 723 37.3 191.0 1.0 4.9 44 34 X 33 2.20 0.81 0.23 — 1.50 712 39.3 19 0.5 0.5 5.5 3454 ◯ 34 2.90 1.07 — 0.30 2.02 733 38.3 19 0.5 0.5 3.9 54 43 ◯

TABLE 3 Ni Ti Adhesiveness This (mass (mass Sn Si Zn TS EC SR R/t R/t GSPPT PPT of invention %) %) (mass %) (mass %) (mass %) (MPa) (% IACS) (%)(GW) (BW) (μm) (nm) (×10¹⁰/mm²) solder 40 1.64 0.65 0.08 — 0.43 604 54.720 0.5 0.5 4.4 21 12 ◯ 41 2.16 0.79 0.13 — 0.52 688 51.8 17 0.5 0.5 4.523 105 ◯ 42 2.63 1.03 0.15 — 0.36 705 50.8 14 0.5 0.5 4.5 27 98 ◯ 432.90 1.15 0.19 — 0.42 735 47.6 12 1.0 1.0 4.6 22 15 ◯ 44 1.60 0.67 —0.08 0.47 608 54.9 17 0.5 0.5 4.6 27 66 ◯ 45 2.08 0.86 — 0.12 0.19 67951.7 15 0.5 0.5 4.2 31 24 ◯ 46 2.57 0.96 — 0.14 0.50 697 49.5 11 0.5 0.54.3 43 15 ◯ 47 2.97 1.13 — 0.19 0.58 748 48.7 11 1.0 1.0 4.7 22 15 ◯ 482.08 0.75 0.06 — 0.43 684 53.4 17 0.5 0.5 4.8 45 23 ◯ 49 2.14 0.82 0.15— 0.47 714 50.9 15 0.5 0.5 4.2 33 24 ◯ 50 2.22 0.82 — 0.06 0.43 727 50.417 0.5 0.5 4.5 23 42 ◯ 51 2.25 0.84 — 0.11 0.43 730 49.7 13 0.5 0.5 4.021 45 ◯ 52 2.03 0.76 0.08 0.09 0.52 688 53.0 16 0.5 0.5 4.2 25 16 ◯ 532.13 0.81 0.12 0.11 0.44 698 52.7 12 0.5 0.5 4.6 13 31 ◯ 54 2.02 0.780.07 0.08 0.42 684 53.2 20 0.5 0.5 4.4 15 156 ◯ 55 2.26 0.89 0.09 0.150.63 736 49.4 14 0.5 0.5 4.3 35 264 ◯ 56 2.16 0.65 0.10 — 0.18 714 51.015 0.5 0.5 4.7 9 51 ◯ 57 2.17 0.58 — 0.12 0.63 717 51.0 14 0.5 0.5 4.736 55 ◯

TABLE 4 Ni Ti Sn Adhesiveness Comparative (mass (mass (mass Si Zn TS ECSR R/t R/t GS PPT PPT of example %) %) %) (mass %) (mass %) (MPa) (%IACS) (%) (GW) (BW) (μm) (nm) (×10¹⁰/mm²) solder 60 0.95 0.42 — — 0.37509 58.4 39 0.5 0.5 4.9 27 135 ◯ 61 3.33 1.25 — — 0.25 704 44.3 31 2.02.0 11.5 25 15 ◯ 62 3.59 0.44 — — 0.39 492 41.0 47 1.5 1.5 12.5 23 56 ◯63 2.91 2.50 — — 0.47 688 38.3 32 2.0 2.0 12.2 13 5 ◯ 64 2.27 0.84 0.01— 0.50 705 50.2 33 0.5 0.5 4.4 45 42 ◯ 65 2.18 0.83 0.56 — 0.53 735 41.424 2.0 2.0 4.2 34 12 ◯ 66 2.15 0.82 — 0.01 0.26 626 55.0 39 1.0 1.5 10.527 26 ◯ 67 2.15 0.80 — 0.62 0.47 636 43.2 22 2.0 2.0 10.2 44 66 ◯ 702.31 0.89 0.03 — — 711 50.7 33 0.5 0.5 4.1 34 33 X 71 2.22 0.85 0.26 — —733 42.3 34 0.5 0.5 4.2 45 55 X 72 2.32 0.76 0.38 — 1.47 699 39.0 24 1.01.0 4.9 37 34 ◯ 73 2.33 0.56 — 0.16 1.95 683 36.2 30 2.0 2.0 10.8 55 33◯

As is clear from the Tables 1 and 3, the Examples 1 to 18 and 40 to 57according to the present invention had good properties with a stressrelaxation resistance of 20% or less.

On the contrary, the Comparative Example 21 was poor in the tensilestrength, since a sufficient magnitude of precipitation reinforcementcould not be obtained due to a small amount Ni. In addition, the stressrelaxation rate was poor, since neither Mg nor Zr was added.

Since the Comparative Example 22 required a high temperature and a longtime for the solution heat treatment due to large contents of Ni and Ti,the crystal grains got coarse to make the bending property poor.Further, the electric conductivity was also poor, since excess Ni and Tiwere solute in the host matrix even after the aging treatment. Inaddition, the stress relaxation rate was poor since neither Mg nor Zrwas added.

The Comparative Example 23 was poor in the bending property due tocoarsened crystal grains since a large content of Ni required a solutionheat treatment at a high temperature for a long time. In addition, thetensile strength was poor due to a poor density of the Ni—Tiprecipitates contributing to the strength since the alloy contained anexcess amount of Ni. Further, the electric conductivity was poor due toan excess amount of Ni that was solute in the host matrix even after theaging treatment. Furthermore, the stress relaxation rate was poor sinceneither Mg nor Zr was added.

Since the Comparative Example 24 required a high temperature and longtime of the solution heat treatment due to a large content of Ti, thecrystal grains got coarse to make the bending property poor. Inaddition, the electric conductivity was poor due to an excess amount ofTi that was solute in the host matrix even after the aging treatment.Further, the stress relaxation rate was poor since neither Mg nor Zr wasadded.

The Comparative Example 25 was poor in the stress relaxation rate due toa small amount of precipitates comprising Ni, Ti and Mg since thecontent of Mg was low.

Both the electric conductivity and the bending property were poor in theComparative Example 26 since excess Mg remained in the solid solution,even after the aging treatment, due to a large content of Mg. Inaddition, the stress relaxation rate was also poor.

Since the Comparative Example 27 contained a small content of Zr, thestress relaxation rate was poor due to a small content of precipitatescomprising Ni, Ti and Zr.

A large content of Zr in the Comparative Example 28 required a hightemperature and long time of the solution heat treatment, so that thebending property was poor due to coarsening of crystal grains. Inaddition, the electric conductivity was poor since excess Zr was solutein the host matrix even after the aging treatment. Further, the stressrelaxation rate was also poor.

A small content of precipitates comprising Ni, Ti, Mg and Zr resulted ina poor stress relaxation rate in the Comparative Example 29, since itcontained a small amount of each of Mg and Zr.

The Comparative Example 30 required a high temperature and long time ofthe solution heat treatment due to a large content of each of Mg and Zr,and the bending property was poor due to coarsening of crystal grains.In addition, the electric conductivity was poor since excess Mg and Zrwere solute in the host matrix even after the aging treatment. Further,the stress relaxation rate was also poor.

The adhesiveness of the solder was deteriorated since no Zn was added inthe Comparative Examples 31 and 32.

The electric conductivity was low in the Comparative Examples 33 and 34since a content of Zn was large.

The above-described Comparative Examples 21 to 34 correspond tocomparative examples that are comparable to the present inventionsdescribed in the above items (1) and (2).

The tensile strength of the Comparative Example 60 was poor since asufficient magnitude of precipitation reinforcement could not beattained due to a small content of Ni. In addition, the stressrelaxation ratio was poor since the density of the Ni—Ti precipitateswas insufficient, and neither Sn nor Si was added.

Since the Comparative Example 61 required a high temperature and a longtime for the solution heat treatment due to large contents of Ni and Ti,the crystal grains got coarse to make the bending property poor.Further, the electric conductivity was also poor, since excess Ni and Tiwere solute in the host matrix even after the aging treatment. Inaddition, the stress relaxation rate was poor since neither Sn nor Siwas added.

The Comparative Example 62 was poor in the bending property due tocoarsened crystal grains since a large content of Ni required a solutionheat treatment at a high temperature for a long time. In addition, thetensile strength was poor due to a low density of the Ni—Ti precipitatescontributing to the strength since the alloy contained an excess amountof Ni. Further, the electric conductivity was poor due to an excessamount of Ni that was solute in the host matrix even after the agingtreatment. Furthermore, the stress relaxation rate was poor sinceneither Sn nor Si was added.

A large content of Ti in the Comparative Example 63 required a hightemperature and long time of the solution heat treatment, so that thebending property was poor due to coarsening of crystal grains. Inaddition, the electric conductivity was poor since excess Ti was solutein the host matrix even after the aging treatment. Further, the stressrelaxation rate was poor since neither Sn nor Si was added.

Since the Comparative Example 64 contained a small content of Sn, thestress relaxation rate was poor due to a small content of precipitatescomprising Ni, Ti and Sn.

Both the electric conductivity and the bending property were poor in theComparative Example 65 since excess Sn remained in the solid solutiondue to a large content of Sn. In addition, the stress relaxation ratewas also poor.

Since the Comparative Example 66 contained a small content of Si, thestress relaxation rate was poor due to a small content of precipitatescomprising Ni, Ti and Si.

A large content of Si in the Comparative Example 67 required a hightemperature and long time of the solution heat treatment, so that thebending property was poor due to coarsening of crystal grains. Inaddition, the electric conductivity was poor since excess Si was solutein the host matrix. Further, the stress relaxation rate was also poor.

The adhesiveness of the solder was deteriorated since no Zn was added inthe Comparative Examples 70 and 71.

The electric conductivity was low in the Comparative Examples 72 and 73since a content of Zn was large.

The above-described Comparative Examples 60 to 67 and 70 to 73correspond to comparative examples that are comparable to the presentinventions described in the above items (3) and (4).

Example 2

The condition for the solution heat treatment and the conditions for thesubsequent cold rolling and aging were variously changed using the alloyhaving the same composition as that of the Sample No. 15 in the Example1 above. Other production conditions were the same as in Example 1. Theevaluation items [1] to [7] were conducted in the same manner as inExample 1. The solution heat conditions and results of the evaluationsare shown in Table 5. TABLE 5 Solution heat treatment Aging Tempe- ColdTempe- EC PPT Adhesive- rature Time Cooling rolling rature Time TS (% SRR/t R/t GS PPT (×10¹⁰/ ness (° C.) (sec) ratio (° C./s) ratio (%) (° C.)(hr) (MPa) IACS) (%) (GW) (BW) (μm) (nm) (mm²) of solder This invention81 1000 15 330 20 550 2 690 52.9 18 0.75 0.75 6 17 187 ◯ 82 950 30 11030 475 1 688 52.0 19 0.5 0.75 5 18 118 ◯ 83 950 15 70 10 550 2 677 54.118 0.5 0.5 5 13 231 ◯ 84 900 15 100 35 500 3 654 56.3 20 0.5 0.5 3 12210 ◯ 85 950 5 200 25 525 1.5 690 52.9 19 0.5 0.5 4 11 103 ◯ 86 850 15150 10 550 3 689 53.0 18 0.5 0.5 5 12 129 ◯ 87 950 15 300 20 525 3.5 68153.8 19 0.5 0.5 4 13 165 ◯ 88 950 15 200 0 475 4 602 50.3 17 0 0 6 12229 ◯ Compar- ative example 91 950 15 35 20 525 3 622 57.2 24 0.5 0.5 513 65 ◯ 92 900 15 25 20 525 3 612 58.0 27 0.5 0.75 5 12 77 ◯ 93 800 15110 20 525 3 639 56.9 26 0.75 0.75 3 10 52 ◯ 94 800 30 105 20 525 3 62956.0 28 0.75 0.75 5 11 49 ◯ 95 950 60 130 20 525 3 690 52.9 18 1.5 1.511 12 223 ◯ 96 -None- -None- -None- >90 525 3 634 58.3 33 >2 >2 — 8 169◯ 97 950 15 200 60 525 3 612 59.0 33 >2 >2 4 12 128 ◯ 98 950 15 200 20625 3 561 59.4 34 0.75 0.75 6 667 4 ◯ 99 950 15 200 20 400 3 533 47.0 420.75 0.75 8 2 321 ◯ 100  950 15 200 20 525 7 553 59.7 32 0.75 0.75 3 3333 ◯

Table 5 shows that the Examples 81 to 88 had excellent properties.

On the contrary, the stress relaxation rate was poor in the ComparativeExamples 91 and 92 since the precipitates got coarse due to the slowcooling rate.

The smaller amount of elements contributing to the precipitation was inthe solid solution due to the low solution heat temperature in theComparative Example 93, and, therefore, the stress relaxation rate waspoor since the precipitation density was decreased at the time of agingtreatment.

The smaller amount of elements contributing to the precipitation was inthe solid solution due to the low solution heat temperature in theComparative Example 94, and, therefore, the stress relaxation rate waspoor since the precipitation density was decreased at the time ofsolution heat treatment.

The bending property was poor in the Comparative Example 95 due tocoarsening of crystal grains since the solution heat time was long.

There caused no recrystallization in the Comparative Example 96 since nosolution heat treatment was conducted. Therefore, the measurement of thecrystal grain size was impossible since the crystalline texture wasfibrous as a result of 90% or more of the cold rolling ratio after thehot rolling. In addition, the bending property and the stress relaxationrate were also poor since the number of precipitations contributing toprecipitation was small.

The bending property was poor in the Comparative Example 97 due to highcold rolling ratio after the solution heat treatment.

The strength was poor in the Comparative Example 98 due to coarsening ofprecipitates since the aging temperature was high.

The strength was poor in the Comparative Example 99 due to fine size ofprecipitates since the aging temperature was low.

The strength was poor in the Comparative Example 100 due to coarseningof precipitates since the aging time was long.

The above-described Comparative Examples 91 to 100 correspond tocomparative examples that are comparable to the present inventionsdescribed in the above items (5) and (6).

Example 3

The properties of the product of the present invention, such as highelectric conductivity, excellent strength, and excellent stressrelaxation resistance property, are exhibited by allowing aNi—Ti-series, Ni—Ti—Mg-series, Ni—Ti—Zr-series or other multi-componentintermetallic compounds based on Ni—Ti to finely precipitate in highdensity in the Cu host matrix by a heat treatment for annealing forprecipitation by aging. For this purpose, the amount in the solidsolution of solute atoms should be increased as much as possible in thestate before precipitation by aging, and the electric conductivity as anindex of the degree of the solid solution is preferably 35% IACS orless, more preferably 30% IACS or less. Therefore, conditions applied inthe steps before the heat treatment for precipitation by aging such as[1] casting speed, [2] heating speed, holding temperature and holdingtime for the subsequent homogenization heat treatment and [3] thesubsequent hot rolling, and cooling speed in the hot rolling, wereadjusted as follows.

Each alloy comprising Ni, Ti, Mg, Zn, Sn, Zr, Hf, In and Ag in theamounts as shown in Tables 6 to 10 with the balance of Cu was melted ina high frequency melting furnace, and cast to obtain an ingot with athickness of 30 mm, a width of 100 mm and a length of 150 mm. The ingotwas cooled at a cooling rate of 1 to 100° C./sec.

After annealing the ingot at 800 to 1,050° C. for 1 hour forhomogenization, it was finished to a hot-rolled plate with a thicknessof about 10 mm by hot rolling. The temperature was raised at a ratio of3° C./minute or more.

The hot rolling was conducted at a cooling rate of 10 to 300° C./sec.

Oxide films were removed by shaving both surfaces of the hot-rolledplate at a depth of about 1.0 mm, and a plate with a thickness of 0.1 to2 mm was obtained thereafter by cold rolling. This plate was processedand heat-treated according to any one of the steps 1 to 4, 5-1 to 5-4,6-1 to 6-4 and 7-1 to 7-4 to obtain each test material.

[Step 1]

The plate was subjected to solution heat treatment for 15 to 600 secondsat a temperature of 850 to 1,000° C. in an inert gas followed by coldrolling. Then, the plate was subjected to annealing once forprecipitation by aging at a temperature of 450 to 650° C. within 5hours, and the annealed plate was subjected to final cold rolling at arolling ratio of more than 0% but 30% or less and stress-reliefannealing at 150 to 500° C., to obtain a test material.

[Step 2]

The plate was subjected to solution heat treatment at a temperature of850 to 1,000° C. for 15 to 600 seconds in an inert gas after coldrolling. Then, the plate was alternately subjected to once or more ofcold rolling, and twice or more of annealing for precipitation by agingat a temperature of 450 to 650° C. for within 5 hours. The final agingannealed material was finally cold-rolled at a rolling ratio in therange of more than 0% but 30% or less and subjected to stress-reliefannealing at 150 to 500° C., to obtain a test material.

[Step 3]

The plate after cold rolling was subjected to annealing forprecipitation by aging once at a temperature of 450 to 650° C. forwithin 5 hours. Then, the thus-obtained annealed material was subjectedto final cold rolling at a rolling ratio in the range of 0% to 30% andstress-relief annealing at 150 to 500° C., to obtain a test material.

[Step 4]

The plate was alternately subjected to twice or more of cold rolling,and twice or more of annealing for precipitation by aging at atemperature of 450 to 650° C. for within 5 hours. Then, the final agingannealed material was subjected to final cold rolling at a rolling ratioin the range of more than 0% but 30% or less and stress-relief annealingat 150 to 500° C., to obtain a test material.

[Steps 5-1 to 5-4]

One, or two or more times of the annealing for precipitation by aging inStep 1, Step 2, Step 3 and Step 4 were performed at a temperatureexceeding 650° C. These steps were referred to as Steps 5-1 to 5-4,respectively.

[Steps 6-1 to 6-4]

One, or two or more times of the annealing for precipitation by aging inStep 1, Step 2, Step 3 and Step 4 were performed at a temperature lowerthan 450° C. These steps were referred to as Steps 6-1 to 6-4,respectively.

[Steps 7-1 to 7-4]

In Step 1, Step 2, Step 3 and Step 4, the plates were annealed forprecipitation by aging at a condition of the electric conductivitybefore annealing for precipitation by aging exceeding 35% IACS. Thesesteps were referred to as Steps 7-1 to 7-4, respectively.

Each plate material thus obtained was investigated with respect to [1]tensile strength (TS), [2] electric conductivity (EC), [3] stressrelaxation property (SR), [4] bending property, [5] density ofprecipitates (PPT) and [6] adhesiveness of solder. The evaluationmethods of [1] tensile strength, [2] electric conductivity, [3] stressrelaxation property, [5] density of precipitates and [6] adhesiveness ofsolder were the same as those in Example 1. The evaluation method of theother evaluation item is as follows.

[4] Bending Property (R/t)

The plate material was cut into a size of 0.5 mm in the width and 25 mmin the length, and was bent at an angle W (90°) with the same bendingradius (R) as the plate thickness (t). The presence of cracks at thebent portion was observed using an optical microscope with 50 timesmagnification. With respect to evaluation criteria, samples with nocracks at the surface of the bent portion were evaluated as “◯”, whilesamples with cracks at the surface of the bent portion were evaluated as“x”.

The precipitates were identified in the same manner as in the Example 1.

The results of the evaluations [1] to [6] are listed together in Tables6 to 10. TABLE 6 Zn Mg Ni/Ti Step TS EC Bending Adhesiveness No. Ni mass% Ti mass % mass % mass % ratio No. MPa % IACS SR % property of solderPPT ×10¹²/mm² This invention 201 2.01 0.63 0.51 0.11 3.19 1 655 55.8 16◯ ◯ 1 This invention 202 2.10 0.64 0.52 0.09 3.28 2 702 56.0 16 ◯ ◯ 1This invention 203 1.81 0.56 0.49 0.11 3.23 3 670 61.2 19.5 ◯ ◯ 1 Thisinvention 204 1.92 0.60 0.50 0.11 3.20 4 688 61.8 19 ◯ ◯ 1 Thisinvention 205 2.30 0.72 0.51 0.11 3.19 3 718 58.7 19 ◯ ◯ 2 Thisinvention 206 2.50 0.78 0.51 0.11 3.21 4 765 56.8 18 ◯ ◯ 3 Thisinvention 207 1.50 0.47 0.52 0.09 3.19 2 668 57.2 16 ◯ ◯ 1 Thisinvention 208 1.30 0.40 0.52 0.09 3.25 2 659 58.1 16 ◯ ◯ 1 Thisinvention 209 1.80 0.50 0.50 0.06 3.60 2 675 57.0 17 ◯ ◯ 1 Thisinvention 210 2.01 0.72 0.51 0.09 2.79 3 670 61.3 19 ◯ ◯ 1 Thisinvention 211 2.03 0.61 1.00 0.11 3.33 4 667 63.1 19.5 ◯ ◯ 1 Thisinvention 212 1.81 0.56 3.00 0.12 3.23 2 685 55.8 17 ◯ ◯ 1 Thisinvention 213 2.03 0.60 0.49 0.15 3.38 4 685 61.5 19 ◯ ◯ 1 Thisinvention 214 1.81 0.60 0.50 0.20 3.02 3 670 61.2 18 ◯ ◯ 1 Thisinvention 215 2.03 0.65 0.51 0.11 3.12 2 675 56.8 15 ◯ ◯ 3 Thisinvention 216 1.81 0.55 0.51 0.12 3.29 3 666 61.1 19.5 ◯ ◯ 0.3Comparative 3.31 1.03 0.50 0.08 3.21 2 715 49.1 21 X ◯ 4 example 217Comparative 0.71 0.22 0.51 0.09 3.23 2 620 58.1 24 ◯ ◯ 0.1 example 218Comparative 2.01 0.37 0.48 0.09 5.43 3 655 51.3 27 ◯ ◯ 1 example 219Comparative 2.03 1.35 0.50 0.12 1.50 3 660 48.2 22 ◯ ◯ 1 example 220Comparative 1.81 0.52 0.00 0.12 3.48 2 665 58.6 20 ◯ X 1 example 221Comparative 1.90 0.60 0.52 0.00 3.17 3 550 61.3 44 ◯ ◯ 1 example 222Comparative 1.91 0.62 0.55 0.01 3.08 2 565 56.3 38 ◯ ◯ 1 example 223Comparative 1.91 0.63 0.56 0.50 3.03 2 670 45.4 19 X ◯ 1 example 224Comparative 1.95 0.66 0.51 0.10 2.95 3 621 43.1 27 ◯ ◯ 0.0001 example225 Comparative 2.01 0.60 0.52 0.13 3.35 4 670 56.8 22 X ◯ 100 example226 Comparative 1.81 0.52 7.02 0.10 3.48 2 651 45.2 22 ◯ ◯ 1 example226-1

TABLE 7 Ni mass Ti Zn Mg Sn Ni/Ti Step TS EC Bending Adhesiveness No. %mass % mass % mass % mass % ratio No. MPa % IACS SR % property of solderPPT ×10¹²/mm² This invention 227 2.01 0.63 0.51 0.11 0.15 3.19 1 68555.6 16 ◯ ◯ 1 This invention 228 2.10 0.64 0.52 0.09 0.2 3.28 2 693 56.416 ◯ ◯ 1 This invention 229 1.81 0.56 0.49 0.11 0.3 3.23 3 688 60.1 18 ◯◯ 1 This invention 230 1.92 0.60 0.50 0.11 0.12 3.20 4 690 59.6 19 ◯ ◯ 1This invention 231 2.01 0.63 0.51 0.11 0.08 3.19 2 666 55.7 16 ◯ ◯ 1This invention 232 2.10 0.64 0.52 0.09 0.09 3.28 2 710 55.9 16 ◯ ◯ 1This invention 233 1.81 0.56 0.49 0.11 0.07 3.23 3 680 60.2 19 ◯ ◯ 1This invention 234 1.92 0.60 0.50 0.11 0.08 3.20 4 695 61.1 19 ◯ ◯ 1This invention 235 2.30 0.72 0.51 0.11 0.08 3.19 3 725 58.0 19 ◯ ◯ 2This invention 236 2.50 0.78 0.51 0.11 0.09 3.21 4 770 56.1 18 ◯ ◯ 3This invention 237 1.50 0.47 0.52 0.09 0.07 3.19 2 675 56.5 16 ◯ ◯ 1This invention 238 1.30 0.40 0.52 0.09 0.08 3.25 2 670 58.0 16 ◯ ◯ 1This invention 239 1.80 0.50 0.50 0.06 0.08 3.60 2 686 56.3 17 ◯ ◯ 1This invention 240 2.01 0.72 0.51 0.09 0.09 2.79 3 682 60.5 19 ◯ ◯ 1This invention 241 2.03 0.61 1.00 0.11 0.07 3.33 4 680 62.5 19.5 ◯ ◯ 1This invention 242 1.81 0.56 3.00 0.12 0.08 3.23 2 693 55.6 17 ◯ ◯ 1This invention 243 2.03 0.60 0.49 0.15 0.08 3.38 4 695 60.7 19 ◯ ◯ 1This invention 244 1.81 0.60 0.50 0.20 0.09 3.02 3 681 60.6 19 ◯ ◯ 1This invention 245 2.03 0.65 0.51 0.11 0.07 3.12 2 686 56.5 15 ◯ ◯ 3This invention 246 1.81 0.55 0.51 0.12 0.08 3.29 3 678 60.3 19.5 ◯ ◯ 0.3Comparative 3.31 1.03 0.50 0.08 0.09 3.21 2 715 49.1 22 X ◯ 4 example247 Comparative 0.71 0.22 0.51 0.09 0.07 3.23 2 620 58.9 25 ◯ ◯ 0.1example 248 Comparative 2.01 0.37 0.48 0.09 0.08 5.43 3 655 50.5 28 ◯ ◯1 example 249 Comparative 2.03 1.35 0.50 0.12 0.08 1.50 3 660 48.1 22 ◯◯ 1 example 250 Comparative 1.81 0.52 0.00 0.12 0.09 3.48 2 665 59.1 20◯ X 1 example 251 Comparative 1.90 0.60 0.52 0.00 0.07 3.17 3 550 52.245 ◯ ◯ 1 example 252 Comparative 1.91 0.62 0.55 0.01 0.08 3.08 2 56550.9 38 ◯ ◯ 1 example 253 Comparative 1.91 0.63 0.56 0.50 0.09 3.03 2670 45.1 20 X ◯ 1 example 254 Comparative 1.95 0.66 0.51 0.10 0.07 2.953 621 47.8 27 ◯ ◯ 0.0001 example 255 Comparative 2.01 0.60 0.52 0.130.08 3.35 4 670 56.1 22 X ◯ 100 example 256 Comparative 1.81 0.52 0.520.12 2 3.48 2 680 48.1 20 ◯ ◯ 1 example 257 Comparative 1.90 0.60 0.520.12 1.51 3.17 3 675 40.2 20 ◯ ◯ 1 example 258 Comparative 1.81 0.527.02 0.10 0.09 3.48 2 651 43.2 22 ◯ ◯ 1 example 258-1

TABLE 8 Ni Ti Zn Mg Other Ni/Ti Step TS EC Bending Adhesiveness PPT×10¹²/ No. mass % mass % mass % mass % mass % ratio No. MPa % IACS SR %property of solder mm² This invention 259 1.82 0.59 0.52 0.08 0.05 Zr3.08 2 692 56.8 18 ◯ ◯ 1 This invention 260 1.85 0.51 0.55 0.09 0.04 Hf3.63 3 685 60.5 19.5 ◯ ◯ 1 This invention 261 1.79 0.53 0.52 0.12 0.05In 3.38 4 680 62.2 19 ◯ ◯ 1 This invention 262 1.79 0.53 0.52 0.12 0.1Ag 3.38 4 702 60.2 19 ◯ ◯ 1 Comparative 1.82 0.59 0.52 0.08 1.02 Zr 3.082 675 46.2 20 X ◯ 1 example 263 Comparative 1.85 0.51 0.55 0.09 1.10 Hf3.63 3 670 44.3 22 X ◯ 1 example 264 Comparative 1.79 0.53 0.52 0.121.20 In 3.38 4 676 38.9 21 X ◯ 1 example 265 Comparative 1.79 0.53 0.520.12 1.3 Ag 3.38 4 685 48.0 20 X ◯ 1 example 266

TABLE 9 Ni Ti Zn mass mass mass Mg Sn Other Ni/Ti Step TS EC BendingAdhesiveness PPT ×10¹²/ No. % % % mass % mass % mass % ratio No. MPa %IACS SR % property of solder mm² This invention 267 1.82 0.59 0.52 0.080.09 0.05 Zr 3.08 2 702 56.1 18 ◯ ◯ 1 This invention 268 1.85 0.51 0.550.09 0.07 0.04 Hf 3.63 3 693 59.5 19.5 ◯ ◯ 1 This invention 269 1.790.53 0.52 0.12 0.09 0.05 In 3.38 4 690 61.1 19 ◯ ◯ 1 This invention 2701.79 0.53 0.52 0.12 0.09 0.1 Ag 3.38 4 705 59.5 19 ◯ ◯ 1 Comparative1.82 0.59 0.52 0.08 0.09 1.02 Zr 3.08 2 680 45.5 20 X ◯ 1 example 271Comparative 1.85 0.51 0.55 0.09 0.07 1.10 Hf 3.63 3 675 42.5 22 X ◯ 1example 272 Comparative 1.79 0.53 0.52 0.12 0.09 1.20 In 3.38 4 684 39.021 X ◯ 1 example 273 Comparative 1.79 0.53 0.52 0.12 0.09 1.3 Ag 3.38 4692 45.3 20 X ◯ 1 example 274

TABLE 10 Ni Ti Zn Mg Sn Ni/Ti Step TS EC Bending Adhesiveness No. mass %mass % mass % mass % mass % ratio No. MPa % IACS SR % property of solderPPT ×10¹²/mm² Comparative 2.01 0.63 0.51 0.11 — 3.19 5-1 556 65.1 28 ◯ ◯0.0004 example 275 Comparative 1.81 0.56 0.49 0.11 — 3.23 5-2 540 66.027 ◯ ◯ 0.0003 example 276 Comparative 1.81 0.56 0.49 0.11  0.08 3.23 5-3570 65.1 29 ◯ ◯ 0.0003 example 277 Comparative 2.01 0.63 0.51 0.11 —3.19 6-1 535 44.2 30 ◯ ◯ 0.0002 example 278 Comparative 1.81 0.56 0.490.11 — 3.23 6-3 542 42.5 32 ◯ ◯ 0.0001 example 279 Comparative 1.81 0.560.49 0.11  0.08 3.23 6-2 551 41.8 30 ◯ ◯ 0.0001 example 280 Comparative2.01 0.63 0.51 0.11 — 3.19 7-4 575 66.2 28 ◯ ◯ 0.0001 example 281Comparative 1.81 0.56 0.49 0.11 — 3.23 7-3 545 68.1 29 ◯ ◯ 0.0001example 282 Comparative 1.81 0.56 0.49 0.11  0.08 3.23 7-2 560 65.1 28 ◯◯ 0.0001 example 283 This 2.01 0.63 0.51 0.11 — 3.19 1 655 55.8 16 ◯ ◯ 1invention 201 This 2.10 0.64 0.52 0.09 0.2 3.28 2 693 56.4 16 ◯ ◯ 1invention 228 This 1.81 0.56 0.49 0.11 0.3 3.23 3 688 60.1 18 ◯ ◯ 1invention 229 This 1.92 0.60 0.50 0.11 — 3.20 4 688 61.8 19 ◯ ◯ 1invention 204

As is clear from Table 6, the Examples 201 to 216 according to thepresent invention had excellent properties, such as tensile strength of650 MPa or more, electric conductivity of 55% IACS or more and stressrelaxation rate of 20% or less.

On the contrary, high temperature and long time of solution heattreatment was necessary due to a large content of Ni in the ComparativeExample 217, and the bending property was poor as a result of coarseningof crystal grains. Further, the electric conductivity was also poorsince an amount of Ni in the solid solution was large.

The Comparative Example 218 was poor in the tensile strength, since asufficient magnitude of precipitation reinforcement could not beobtained due to a small amount Ni.

The electric conductivity was poor in the Comparative Examples 219 and220 due to an increased amount of elements in the solid solution sincethe Ni/Ti ratio was out of the range prescribed in the presentinvention.

The adhesiveness of solder was deteriorated in the Comparative Example221 since no Zn was added.

The strength of the Comparative Examples 222 and 223 was insufficientdue to a small amount of precipitates comprising Ni, Ti and Mg since noMg or a too small amount of Mg was added. In addition, the stressrelaxation rate was also poor due to a small amount of Mg in the solidsolution.

Excess Mg remained in the solid solution even by aging treatment in theComparative Example 224 since the amount of Mg was in excess, so thatboth the electric conductivity and the bending property were poor.

The strength and the stress relaxation rate were poor in the ComparativeExample 225 since the density of precipitates was low.

Coarse precipitates were readily formed at grain boundaries in theComparative Example 226 due to a high density of precipitates, so thatthe bending property was poor.

The electric conductivity was decreased in the Comparative Example 226-1since a large amount of Zn added caused Zn to remain in the solidsolution.

The above-described Comparative Examples 217 to 226 and 226-1 correspondto comparative examples that are comparable to the present inventionsdescribed in the above item (7).

As is clear from Table 7, the Examples 227 to 246 according to thepresent invention had excellent properties, such as tensile strength of650 MPa or more, electric conductivity of 55% IACS or more and stressrelaxation rate of 20% or less.

On the contrary, high temperature and long time of solution heattreatment was necessary due to a large content of Ni in the ComparativeExample 247, and the bending property was poor as a result of coarseningof crystal grains. Further, the electric conductivity was also poorsince an amount of Ni in the solid solution was large.

The Comparative Example 248 was poor in the tensile strength, since asufficient magnitude of precipitation reinforcement could not beobtained due to a small amount Ni.

The electric conductivity was poor in the Comparative Examples 249 and250 due to an increased amount of elements in the solid solution sincethe Ni/Ti ratio was out of the range prescribed in the presentinvention.

The adhesiveness of solder was deteriorated in the Comparative Example251 since no Zn was added.

The strength of the Comparative Examples 252 and 253 was insufficientdue to a small amount of precipitates comprising Ni, Ti and Mg since noMg or a too small amount of Mg was added. In addition, the stressrelaxation rate was also poor due to a small amount of Mg in the solidsolution.

Excess Mg remained in the solid solution even by aging treatment in theComparative Example 254 since the amount of Mg was in excess, so thatboth the electric conductivity and the bending property were poor.

The strength and the stress relaxation rate were poor in the ComparativeExample 255 since the density of precipitates was low.

Coarse precipitates were readily formed at grain boundaries in theComparative Example 256 due to a high density of precipitates, so thatthe bending property was poor.

The electric conductivity was poor in the Comparative Examples 257 and258, since an amount of Sn was large.

The electric conductivity was decreased in the Comparative Example 258-1since a large amount of Zn added caused Zn to remain in the solidsolution.

The above-described Comparative Examples 247 to 258 and 258-1 correspondto comparative examples that are comparable to the present inventiondescribed in the above item (8).

As is clear from Table 8, the Examples 259 to 262 according to thepresent invention had excellent properties, such as tensile strength of650 MPa or more, electric conductivity of 55% IACS or more and stressrelaxation rate of 20% or less.

On the contrary, an excess amount of Zr in the Comparative Example 263caused excess Zr to remain in the solid solution to deteriorate both theelectric conductivity and the bending property.

An excess amount of Hf in the Comparative Example 264 caused excess Hfto remain in the solid solution to deteriorate both the electricconductivity and the bending property.

An excess amount of In in the Comparative Example 265 caused excess Into remain in the solid solution to deteriorate both the electricconductivity and the bending property.

An excess amount of Ag in the Comparative Example 266 caused excess Agto remain in the solid solution to deteriorate both the electricconductivity and the bending property.

The above-described Comparative Examples 263 to 266 correspond tocomparative examples that are comparable to the present inventiondescribed in the above item (9).

As is clear from Table 9, the Examples 267 to 270 according to thepresent invention had excellent properties, such as tensile strength of650 MPa or more, electric conductivity of 55% IACS or more and stressrelaxation rate of 20% or less.

On the contrary, an excess amount of Zr in the Comparative Example 271caused excess Zr to remain in the solid solution to deteriorate both theelectric conductivity and the bending property.

An excess amount of Hf in the Comparative Example 272 caused excess Hfto remain in the solid solution to deteriorate both the electricconductivity and the bending property.

An excess amount of In in the Comparative Example 273 caused excess Into remain in the solid solution to deteriorate both the electricconductivity and the bending property.

An excess amount of Ag in the Comparative Example 274 caused excess Agto remain in the solid solution to deteriorate both the electricconductivity and the bending property.

The above-described Comparative Examples 271 to 274 correspond tocomparative examples that are comparable to the present inventiondescribed in the above item (10).

As is clear from Table 10, the Examples 201, 228, 229 and 204 accordingto the present invention had excellent properties, such as tensilestrength of 650 MPa or more, electric conductivity of 55% IACS or moreand stress relaxation rate of 20% or less.

On the contrary, the density of precipitates was low due to a too highaging temperature in the Comparative Examples 275 to 277, and thestrength and the stress relaxation rate were poor.

The amount of precipitates was insufficient due to a too low agingtemperature in the Comparative Example 278 to 280, so that the densityof the precipitates was low to result in poor strength, electricconductivity and stress relaxation rate.

The density of the precipitate after the heat treatment forprecipitation by aging was low and the strength and stress relaxationrate was poor in the Comparative Examples 281 to 283, since the sampleshaving an electric conductivity of 35% IACS or more before the heattreatment for precipitation by aging were subjected to the heattreatment for precipitation by aging.

The above-described Comparative Examples 275 to 283 correspond tocomparative examples that are comparable to the present inventiondescribed in the above item (11).

INDUSTRIAL APPLICABILITY

The copper alloy of the present invention can be favorably applied forconnectors of electric and electronic instruments, connectors ofterminals, materials of terminals, and the like.

Having described our invention as related to the present embodiments, itis our intention that the invention not be limited by any of the detailsof the description, unless otherwise specified, but rather be construedbroadly within its spirit and scope as set out in the accompanyingclaims.

This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2004-165068 filed in Japan on Jun. 2,2004, and Patent Application No. 2005-161475 filed in Japan on Jun. 1,2005, each of which is entirely herein incorporated by reference.

1. A copper alloy for electric and electronic instruments, comprising Niof 1 to 3 mass %, Ti of 0.2 to 1.2 mass %, any one or both of Mg and Zrof 0.02 to 0.2 mass %, and Zn of 0.1 to 1 mass %, with the balance beingCu and unavoidable impurities, wherein the copper alloy contains atleast one of an intermetallic compound comprising Ni, Ti and Mg, anintermetallic compound comprising Ni, Ti and Zr, or an intermetalliccompound comprising Ni, Ti, Mg and Zr, and wherein the copper alloy hasa stress relaxation rate of 20% or less after holding the alloy at 150°C. for 1,000 hours.
 2. The copper alloy for electric and electronicinstruments according to claim 1, wherein the intermetallic compoundcomprising Ni, Ti and Mg, the intermetallic compound comprising Ni, Tiand Zr, or the intermetallic compound comprising Ni, Ti, Mg and Zr hasan average particle diameter in the range from 5 to 100 nm and adistribution density of from 1×10¹⁰ to 1×10¹³/mm², and wherein thecrystal grain size of a host matrix of the alloy is 10 μm or less.
 3. Acopper alloy for electric and electronic instruments, comprising Ni of 1to 3 mass %, Ti of 0.2 to 1.2 mass %, any one or both of Sn and Si of0.02 to 0.2 mass %, and Zn of 0.1 to 1 mass %, with the balance being Cuand unavoidable impurities, wherein the copper alloy contains at leastone of an intermetallic compound comprising Ni, Ti and Sn, anintermetallic compound comprising Ni, Ti and Si, or an intermetalliccompound comprising Ni, Ti, Sn and Si, and wherein the copper alloy hasa stress relaxation rate of 20% or less after holding the alloy at 150°C. for 1,000 hours.
 4. The copper alloy for electric and electronicinstruments according to claim 3, wherein the intermetallic compoundcomprising Ni, Ti and Sn, the intermetallic compound comprising Ni, Tiand Si, or the intermetallic compound comprising Ni, Ti, Sn and Si hasan average particle diameter in the range from 5 to 100 nm and adistribution density of from 1×10¹⁰ to 1×10¹³/mm², and wherein thecrystal grain size of a host matrix of the alloy is 10 μm or less. 5-11.(canceled)
 12. A method of producing the copper alloy for electric andelectronic instruments according to claim 1, comprising the steps of:conducting a solution heat treatment at a temperature of 850° C. or morefor 35 seconds or less, cooling from the solution heat treatmenttemperature to 300° C. at a cooling rate of 50° C./sec or more,cold-rolling at a cold rolling ratio in the range of more than 0% but50% or less, and aging at a temperature in the range from 450 to 600° C.within 5 hours.
 13. A method of producing the copper alloy for electricand electronic instruments according to claim 2, comprising the stepsof: conducting a solution heat treatment at a temperature of 850° C. ormore for 35 seconds or less, cooling from the solution heat treatmenttemperature to 300° C. at a cooling rate of 50° C./sec or more,cold-rolling at a cold rolling ratio in the range of more than 0% but50% or less, and aging at a temperature in the range from 450 to 600° C.within 5 hours.
 14. A method of producing the copper alloy for electricand electronic instruments according to claim 3, comprising the stepsof: conducting a solution heat treatment at a temperature of 850° C. ormore for 35 seconds or less, cooling from the solution heat treatmenttemperature to 300° C. at a cooling rate of 50° C./sec or more,cold-rolling at a cold rolling ratio in the range of more than 0% but50% or less, and aging at a temperature in the range from 450 to 600° C.within 5 hours.
 15. A method of producing the copper alloy for electricand electronic instruments according to claim 4, comprising the stepsof: conducting a solution heat treatment at a temperature of 850° C. ormore for 35 seconds or less, cooling from the solution heat treatmenttemperature to 300° C. at a cooling rate of 50° C./sec or more,cold-rolling at a cold rolling ratio in the range of more than 0% but50% or less, and aging at a temperature in the range from 450 to 600° C.within 5 hours.
 16. A method of producing the copper alloy for electricand electronic instruments according to claim 1, comprising the stepsof: conducting a solution heat treatment at a temperature of 850° C. ormore for 35 seconds or less, cooling from the solution heat treatmenttemperature to 300° C. at a cooling rate of 50° C./sec or more, andaging at a temperature in the range from 450 to 600° C. within 5 hours.17. A method of producing the copper alloy for electric and electronicinstruments according to claim 2, comprising the steps of: conducting asolution heat treatment at a temperature of 850° C. or more for 35seconds or less, cooling from the solution heat treatment temperature to300° C. at a cooling rate of 50° C./sec or more, and aging at atemperature in the range from 450 to 600° C. within 5 hours.
 18. Amethod of producing the copper alloy for electric and electronicinstruments according to claim 3, comprising the steps of: conducting asolution heat treatment at a temperature of 850° C. or more for 35seconds or less, cooling from the solution heat treatment temperature to300° C. at a cooling rate of 50° C./sec or more, and aging at atemperature in the range from 450 to 600° C. within 5 hours.
 19. Amethod of producing the copper alloy for electric and electronicinstruments according to claim 4, comprising the steps of: conducting asolution heat treatment at a temperature of 850° C. or more for 35seconds or less, cooling from the solution heat treatment temperature to300° C. at a cooling rate of 50° C./sec or more, and aging at atemperature in the range from 450 to 600° C. within 5 hours.
 20. Acopper alloy for electric and electronic instruments, comprising Ni of 1to 3 mass % and Ti of 0.2 to 1.4 mass % with a ratio (Ni/Ti) of the masspercentage between Ni and Ti in the range from 2.2 to 4.7, any one orboth of Mg and Zr in a total amount of 0.02 to 0.3 mass %, and Zn of 0.1to 5 mass %, with the balance being Cu and unavoidable impurities,wherein the copper alloy contains at least one of an intermetalliccompound comprising Ni, Ti and Mg, an intermetallic compound comprisingNi, Ti and Zr or an intermetallic compound comprising Ni, Ti, Mg and Zr,and wherein the copper alloy has a distribution density of theintermetallic compound in the range from 1×10⁹ to 1×10¹³/mm², a tensilestrength of 650 MPa or more, an electric conductivity of 55% IACS ormore, and a stress relaxation rate of 20% or less after holding thealloy at 150° C. for 1,000 hours.
 21. A copper alloy for electric andelectronic instruments, comprising Ni of 1 to 3 mass % and Ti of 0.2 to1.4 mass % with a ratio (Ni/Ti) of the mass percentage between Ni and Tiin the range from 2.2 to 4.7, any one or both of Mg and Zr in a totalamount of 0.02 to 0.3 mass %, Zn of 0.1 to 5 mass %, and Sn in the rangeof more than 0 mass % but 0.5 mass % or less, with the balance being Cuand unavoidable impurities, wherein the copper alloy contains at leastone of an intermetallic compound comprising Ni, Ti and Mg, anintermetallic compound comprising Ni, Ti and Zr or an intermetalliccompound comprising Ni, Ti, Mg and Zr, and wherein the copper alloy hasa distribution density of the intermetallic compound in the range from1×10⁹ to 1×10¹³/mm², a tensile strength of 650 MPa or more, an electricconductivity of 55% IACS or more, and a stress relaxation rate of 20% orless after holding the alloy at 150° C. for 1,000 hours.
 22. A copperalloy for electric and electronic instruments, comprising Ni of 1 to 3mass % and Ti of 0.2 to 1.4 mass % with a ratio (Ni/Ti) of the masspercentage between Ni and Ti in the range from 2.2 to 4.7, Mg of 0.02 to0.3 mass %, Zn of 0.1 to 5 mass %, and any one or at least two of Zr,Hf, In and Ag in a total amount of more than 0 mass % but 1.0 mass % orless, with the balance being Cu and unavoidable impurities, wherein thecopper alloy contains at least one of an intermetallic compoundcomprising Ni, Ti and Mg, an intermetallic compound comprising Ni, Tiand Zr, or an intermetallic compound comprising Ni, Ti, Mg and Zr, andwherein the copper alloy has a distribution density of the intermetalliccompound in the range from 1×10⁹ to 1×10¹³/mm², a tensile strength of650 MPa or more, an electric conductivity of 55% IACS or more, and astress relaxation rate of 20% or less after holding the alloy at 150° C.for 1,000 hours.
 23. A copper alloy for electric and electronicinstruments, comprising Ni of 1 to 3 mass % and Ti of 0.2 to 1.4 mass %with a ratio (Ni/Ti) of the mass percentage between Ni and Ti in therange from 2.2 to 4.7, Mg of 0.02 to 0.3 mass %, Zn of 0.1 to 5 mass %,Sn in the range of more than 0 mass % but 0.5 mass % or less, and anyone or at least two of Zr, Hf, In and Ag in a total amount of more than0 mass % but 1.0 mass % or less, with the balance being Cu andunavoidable impurities, wherein the copper alloy contains at least oneof an intermetallic compound comprising Ni, Ti and Mg, an intermetalliccompound comprising Ni, Ti and Zr, or an intermetallic compoundcomprising Ni, Ti, Mg and Zr, and wherein the copper alloy has adistribution density of the intermetallic compound in the range from1×10⁹ to 1×10¹³/mm², a tensile strength of 650 MPa or more, an electricconductivity of 55% IACS or more, and a stress relaxation rate of 20% orless after holding the alloy at 150° C. for 1,000 hours.
 24. A method ofproducing the copper alloy for electric and electronic instrumentsaccording to claim 20, which comprises applying once or at least twiceof heat treatment for precipitation by aging at a temperature of from450 to 650° C. within 5 hours, wherein an electric conductivity beforethe heat treatment for precipitation by aging is 35% IACS or less.
 25. Amethod of producing the copper alloy for electric and electronicinstruments according to claim 21, which comprises applying once or atleast twice of heat treatment for precipitation by aging at atemperature of from 450 to 650° C. within 5 hours, wherein an electricconductivity before the heat treatment for precipitation by aging is 35%IACS or less.
 26. A method of producing the copper alloy for electricand electronic instruments according to claim 22, which comprisesapplying once or at least twice of heat treatment for precipitation byaging at a temperature of from 450 to 650° C. within 5 hours, wherein anelectric conductivity before the heat treatment for precipitation byaging is 35% IACS or less.
 27. A method of producing the copper alloyfor electric and electronic instruments according to claim 23, whichcomprises applying once or at least twice of heat treatment forprecipitation by aging at a temperature of from 450 to 650° C. within 5hours, wherein an electric conductivity before the heat treatment forprecipitation by aging is 35% IACS or less.